# Social media glossary More than 110 social media terms in plain language, from reach and engagement rate to hashtags, ad metrics, webhooks and MCP. Search the list, filter by category, or link straight to a term. Last verified: 2026-10-17 ## A ### A/B test Showing two versions of an ad or post that differ in one thing (image, hook, headline) to see which does better. Category: Ads ### Accessibility Making posts usable by everyone, including people with screen readers: alt text on images, captions on videos, CamelCase hashtags and plain letters instead of Unicode-styled text. Category: Content. Source: https://axbom.com/dont-fake-bold-and-italic-text-with-unicode ### Ad creative The visible part of an ad: the image or video, the text, the headline and the button. Category: Ads ### Ad set The level of a Meta ad campaign that holds the audience, budget, schedule and placements; the ads sit inside it. Category: Ads ### AI agent An AI assistant that takes actions for you through tools, such as drafting and scheduling posts, not only writing text. Give it limited permissions and keep a person approving what it publishes. Category: Strategy. Source: https://genai.owasp.org/llmrisk/llm062025-excessive-agency/ ### Algorithm The ranking system that decides which posts each person sees and in what order, based on signals such as past interactions and how others respond to the post. Category: Platforms ### Alt text A written description of an image for people who use screen readers or cannot load images. Most networks have a field for it next to the image. Category: Content ### API An application programming interface: a set of rules that lets one program ask another for data or actions. A social media API lets your code create, schedule and read posts. Category: Developer. Source: https://postboost.co/docs ### API key (access token) A secret string that identifies your app or account to an API, sent with each request. PostBoost tokens go in the Authorization header as a Bearer token; treat them like passwords. Category: Developer. Source: https://postboost.co/docs/authentication ### Approval workflow A step where a post waits for someone with permission to approve it before it can be scheduled or published. Category: Strategy ### Aspect ratio The ratio of an image's or video's width to its height, such as 1:1, 4:5 or 9:16. A network crops or rejects media outside the ratios it supports. Category: Content. Source: https://www.facebook.com/help/instagram/1631821640426723 ### AT Protocol The open protocol under Bluesky. Apps such as schedulers connect to a Bluesky account with OAuth instead of asking for your password. Category: Platforms. Source: https://atproto.com/specs/oauth ### Attribution Deciding which channel, campaign or post gets the credit for a visit, signup or sale. On social it usually rests on UTM-tagged links or an ad network's own tracking. Category: Metrics. Source: https://support.google.com/analytics/answer/9756891 ### Audience retention How much of a video viewers watch before they leave, often shown as a curve over the video's length. A sharp early drop usually points to a weak opening. Category: Metrics ## B ### Best time to post The days and hours when your audience is most likely to see and react to a post. Industry studies give a starting point, and your own analytics refine it. Category: Strategy. Source: https://buffer.com/resources/best-time-to-post-on-linkedin/ ### Bio The short description on your profile that says who you are and why to follow you, usually with one link. Category: Platforms ### Bluesky An open social network built on the AT Protocol, where a post holds up to 300 graphemes. Category: Platforms. Source: https://github.com/bluesky-social/atproto/blob/main/packages/api/lexicons/app/bsky/feed/post.json ### Boosted post An organic post you pay to show to more people, chosen from your page or profile instead of built from scratch in an ads manager. Category: Ads ### Brand voice The consistent personality and tone in everything a brand writes. Writing it down (audience, topics, words to use and avoid) keeps people and AI tools on tone. Category: Strategy ## C ### Call to action (CTA) The one thing a post asks the reader to do next, such as read the article, comment or sign up. One clear ask works better than several. Category: Content ### Caption The text that goes with an image or video post. Captions carry the hook, the context, hashtags and mentions, within each network's character limit. Category: Content ### Carousel A single post that holds several images or videos people swipe through. Instagram carousels hold up to 20 items. Category: Content. Source: https://www.socialmediatoday.com/news/instagram-expands-carousels-to-20-frames/723792/ ### Character limit The most text a network accepts in one post. Networks count differently (characters, bytes or graphemes, with links and emoji weighted on some), and Instagram allows 2,200 characters in a caption. Category: Content. Source: https://developers.facebook.com/docs/instagram-platform/instagram-graph-api/reference/error-codes ### Click-through rate (CTR) Link clicks divided by impressions, as a percentage. It shows how often people who saw a post or ad went on to open its link. Category: Metrics ### Community management Replying to comments and messages, welcoming new followers and moderating, so the audience feels heard. Category: Strategy ### Content calendar A plan of what goes out when and where, usually a month or more ahead, with topics, formats and owners. Category: Strategy ### Content mix The balance of post types you publish, such as how-tos, news, behind-the-scenes and promotion, so the feed is not only selling. Category: Strategy ### Content pillar One of the three to five recurring themes a brand posts about, so the calendar has a clear focus and enough variety. Category: Strategy ### Content recycling Republishing your best evergreen posts on a schedule so new followers see them. In PostBoost a recycling rule reposts one post, or rotates through tagged posts, every 1 to 365 days. Category: Strategy. Source: https://postboost.co/features/automations ### Conversion rate The share of visitors or clicks that complete a goal, such as a signup or purchase. Divide conversions by the visits or clicks that could have converted. Category: Metrics ### Cover image The frame or image shown for a reel or video in the grid and feed. Instagram lets you pick a frame or upload a separate cover. Category: Content. Source: https://www.facebook.com/help/instagram/1038071743007909 ### CPC Cost per click: ad spend divided by the clicks the ad got. Category: Ads ### CPM Cost per mille: what an ad costs for every 1,000 impressions. Category: Ads ## D ### Direct message (DM) A private message between accounts, outside the public feed. Many brands answer support questions there. Category: Platforms ## E ### Endpoint One URL and HTTP method of an API that does one job, such as POST /posts to create a post. Category: Developer. Source: https://postboost.co/docs/api/postboost-api ### Engagement The interactions people have with a post: likes or reactions, comments, shares, saves and, on some networks, clicks. Each network decides which actions it counts, so totals are not directly comparable across networks. Category: Metrics ### Engagement rate Engagements divided by an audience number, shown as a percentage. The audience can be followers, reach or impressions, and each choice gives a different figure, so always say which one a report uses. Category: Metrics ### Engagement rate by reach Engagements on a post divided by the number of people who saw it. It judges how well a piece of content did with the people it actually reached. Category: Metrics ### Evergreen content Posts that stay useful for months, such as how-tos and answers to common questions, so you can share them again later. Category: Content ## F ### Facebook Page A public Facebook presence for a business, brand or public figure, separate from a personal profile. PostBoost publishes to Facebook Pages. Category: Platforms ### Fediverse The group of independent social servers that can follow and reply to each other across services, Mastodon being the best known. Category: Platforms ### Feed The scrolling stream of posts a person sees when they open an app, made of accounts they follow and, more and more, recommendations. Category: Platforms ### First comment A comment the author adds right after a post goes out, often to hold a link or extra hashtags while the post itself stays clean. Category: Content ### Follower growth rate How fast an account gains followers over a period: new followers minus lost followers, divided by the follower count at the start. Category: Metrics ### Followers Accounts that chose to see your posts in their feed. Follower count is the usual base for comparing accounts of different sizes. Category: Metrics ### For You page TikTok's main feed of recommended videos from any account, not only the ones you follow. Other apps have similar recommendation feeds. Category: Platforms ## G ### Google Business Profile A business's listing on Google Search and Maps. You can publish updates and offers to it, and they show on the listing. Category: Platforms ### Grapheme One character as a reader sees it, even if it is stored as several code points, such as an emoji with a skin tone. Bluesky limits posts to 300 graphemes rather than 300 bytes or code points. Category: Content. Source: https://github.com/bluesky-social/atproto/blob/main/packages/api/lexicons/app/bsky/feed/post.json ## H ### Handle Your unique @name on a network, which people type to mention you and which appears in your profile URL. Category: Platforms ### Hashtag A word or phrase after a # sign that groups posts on a topic and makes them findable. Instagram now allows 5 hashtags per post, down from the 30 that older guides mention. Category: Content. Source: https://www.socialmediatoday.com/news/instagram-implements-new-limits-on-hashtag-use/808309/ ### Hashtag group A saved set of hashtags you insert into a post in one step instead of typing them each time. In PostBoost you keep them in the editor and over the API. Category: Content ### Hook The first line of a post or the first seconds of a video, written to make people stop scrolling and read or watch on. Category: Content ### HTTP 429 The status code for Too Many Requests: you hit a rate limit. Wait as long as the Retry-After header says, then retry. Category: Developer. Source: https://postboost.co/docs/rate-limits ### Human in the loop A setup where a person reviews or approves what an automated system or AI agent does before it goes live. Category: Strategy. Source: https://genai.owasp.org/llmrisk/llm062025-excessive-agency/ ## I ### Idempotency key A unique value sent with a request so a retry cannot create a duplicate. In PostBoost, a POST with the same Idempotency-Key and body within 24 hours returns the first response and creates nothing new. Category: Developer. Source: https://postboost.co/docs/errors#idempotent-requests ### Impressions The number of times a post was shown on screen, counting repeat views by the same person. Meta's API no longer reports impressions for Instagram posts created after 2 July 2024; it reports views. Category: Metrics. Source: https://developers.facebook.com/docs/instagram-platform/reference/instagram-media/insights ### Influencer marketing Paying or partnering with creators to show your product to their audience. Price depends on audience size, the deliverable and usage rights. Category: Strategy ### Instagram professional account An Instagram business or creator account. It adds insights and contact options, and only professional accounts can publish through Meta's API. Category: Platforms. Source: https://developers.facebook.com/docs/instagram-platform/content-publishing ## J ### JSON A text format for structured data made of keys and values. Most social media APIs send and receive JSON. Category: Developer ## K ### KPI A key performance indicator: the few numbers you agree to judge a social account by, such as engagement rate, link clicks or signups from social, chosen to match the goal. Category: Metrics ## L ### Link clicks The number of times people opened the link in a post or ad. Tag the link with UTM parameters to see those visits in your web analytics too. Category: Metrics ### Link in bio The one link on your profile. Posts point to it ("link in bio") on networks where a link typed into a caption is not clickable. Category: Platforms ### Link preview The card with a title, image and site name that appears when a post contains a link. The network builds it from the page's Open Graph tags. Category: Content. Source: https://www.linkedin.com/help/linkedin/answer/a521928 ### LinkedIn Page A company's or organisation's presence on LinkedIn, run by admins and separate from members' personal profiles. Category: Platforms. Source: https://www.linkedin.com/help/linkedin/answer/a570460 ### Lookalike audience An ad audience the network builds from people who resemble a source list you give it, such as your customers. Category: Ads ## M ### Mastodon A decentralised social network made of independent servers (instances) that talk to each other, part of the fediverse. Category: Platforms. Source: https://docs.joinmastodon.org/user/posting/ ### MCP (Model Context Protocol) An open protocol that lets AI apps such as Claude call tools on outside services. A social media MCP server lets an assistant draft, schedule and check posts for you. Category: Developer. Source: https://modelcontextprotocol.io/introduction ### MCP server A service that offers tools to AI apps over MCP. PostBoost runs one, so an assistant you connect can create and schedule posts with your token. Category: Developer. Source: https://postboost.co/docs/mcp ### Mention Tagging another account in a post with @ and its handle, so it gets notified and readers can tap through to it. Category: Content ### Mentions Posts that name or tag your account or brand. Counting them over time shows how much people talk about you. Category: Metrics ## O ### OAuth The standard way to let an app act on your account without giving it your password. You approve the app on the network's own page and it gets a token with limited scopes. Category: Developer. Source: https://atproto.com/specs/oauth ### Open Graph tags Meta tags in a web page's HTML (og:title, og:image, og:description) that tell networks what to show in the link preview. Category: Content. Source: https://www.linkedin.com/help/linkedin/answer/a521928 ### OpenAPI A standard file format that describes a REST API's endpoints, parameters and responses, used to generate docs, SDKs and tests. Category: Developer. Source: https://postboost.co/docs/api/postboost-api ## P ### Pin A Pinterest post: an image or video with a title, description and link, saved to a board where people find it through search. Category: Platforms ### Posting frequency How often you publish on each network. Pick a rhythm your team can keep up; consistency matters more than volume. Category: Strategy ### Posting queue A list of preset time slots per account; new posts go into the next free slot instead of being given a time one by one. Category: Strategy ### Profile visits How many times people opened your profile, often after seeing a post. Combined with a link in bio, it is one way social turns into website visits. Category: Metrics ## R ### Rate limit The most requests an API accepts in a time window. Going over it returns HTTP 429 Too Many Requests, and the client should wait for the Retry-After interval before trying again. Category: Developer. Source: https://postboost.co/docs/rate-limits ### Reach The number of unique accounts that saw a post or profile at least once in a period. One person who sees the same post three times counts once. Category: Metrics. Source: https://developers.facebook.com/docs/instagram-platform/reference/instagram-media/insights ### Reel A short vertical video on Instagram or Facebook, shown in its own tab and in the feed, with music, effects and a cover image. Category: Content ### Refresh token A long-lived token an app uses to get a new access token when the old one expires, without asking you to log in again. When it stops working, the account has to be reconnected. Category: Developer ### Repurposing Turning one piece of content, such as a blog post, video or podcast, into several posts shaped for each network. Category: Content ### REST API An API that works over HTTP with URLs for things (posts, accounts) and methods for actions: GET to read, POST to create, PUT or PATCH to update, DELETE to remove. Category: Developer. Source: https://postboost.co/docs ### Retargeting Showing ads to people who already visited your website, used your app or engaged with your posts. Category: Ads ### ROAS Return on ad spend: the revenue an ad campaign brought in divided by what it cost. A ROAS of 3 means 3 dollars back for each dollar spent. Category: Ads ## S ### Safe zone The part of a vertical video or story that the app's buttons, captions and tabs do not cover. Keep text and faces inside it. Category: Content ### Saves How many people bookmarked a post to come back to it. Instagram calls them saves and Pinterest calls them pin saves; a save often signals content people find useful. Category: Metrics ### Scheduling Writing a post now and setting the date and time it publishes, so a tool sends it out even when nobody is at a desk. Category: Strategy ### Scopes The permissions attached to a token or OAuth grant, such as read-only or publish. Give each key or app only the scopes it needs. Category: Developer. Source: https://postboost.co/docs/authentication ### SDK A software development kit: a library for one programming language that wraps an API in ready-made functions. PostBoost publishes SDKs generated from its OpenAPI spec. Category: Developer. Source: https://postboost.co/docs/sdks ### Share of voice Your brand's part of the online conversation in your market compared with competitors, measured by mentions or by paid impressions. Category: Metrics ### Shares How many times people passed a post on: a repost, a send in a direct message or a share to a story, depending on the network. Category: Metrics ### Short-form video Vertical videos of up to a few minutes, made for phones: TikTok videos, Instagram Reels and YouTube Shorts. Category: Content ### Social listening Tracking what people say online about your brand, competitors and topics, including posts that do not tag you, to find trends, questions and problems. Category: Strategy ### Social media audit A review of each profile and its results (bio, links, posting rhythm, replies, formats, engagement) to find what to fix first. Category: Strategy ### Social media management tool Software for running several social accounts from one place: write, schedule, publish, approve and measure posts. PostBoost is one, with a public API and MCP server. Category: Strategy ### Social media ROI Return on investment from social media: the revenue it brought in minus what it cost (ads, tools, hours, content), divided by that cost. Category: Metrics ### Social proof Signals that other people trust a product, such as reviews, customer posts and follower counts, which make newcomers more likely to trust it too. Category: Strategy ### Sponsored content Content a brand pays for, either as an ad or as a paid post by a creator. Networks and many countries' rules require it to be labelled as paid. Category: Ads ### Story A full-screen vertical post that disappears after 24 hours, unless you keep it in a profile highlight. Category: Content. Source: https://help.instagram.com/1729008150678239/ ## T ### Targeting Choosing who sees an ad by location, age, interests, behaviour or by your own customer lists. Category: Ads ### Thread A chain of posts published as replies to one another, used to tell something longer than one post allows. A scheduler should publish the parts in order and pick up from the failed part on a retry. Category: Content ### Threads Meta's text-first app linked to Instagram accounts. A post holds 500 characters, and longer text can go in a text attachment. Category: Platforms. Source: https://developers.facebook.com/documentation/threads/posts ### Thumbnail The still image that stands for a video before someone presses play. YouTube recommends custom thumbnails at 3840 by 2160 pixels (16:9); you need a verified account to upload one. Category: Content. Source: https://support.google.com/youtube/answer/72431 ### Token expiry When a network's access token stops working, after a set time or after a password change or revoked access. Posts to that account fail until it is reconnected, which is why PostBoost shows connection health. Category: Developer ### Topic tag Threads' version of a hashtag: one tag per post that files it under a topic. A tag can be up to 50 characters. Category: Content. Source: https://developers.facebook.com/documentation/threads/posts ### Tracking pixel A snippet of code on your website that reports visits and purchases back to an ad network, so it can measure ads and build retargeting audiences. Category: Ads ## U ### Unicode-styled text Bold, italic or script-looking letters copied from Unicode's math symbol blocks, used where a network has no formatting. Screen readers may read them out letter by letter or skip them, and search may not match them. Category: Content. Source: https://axbom.com/dont-fake-bold-and-italic-text-with-unicode ### User-generated content (UGC) Posts, photos, videos or reviews made by customers or fans rather than the brand. Brands reshare it with permission and credit. Category: Content ### UTM parameters Tags added to the end of a link (utm_source, utm_medium, utm_campaign and others) that tell analytics tools such as Google Analytics where a visit came from. Category: Metrics. Source: https://support.google.com/analytics/answer/10917952 ## V ### Views How many times a post, reel or video was seen. Each network sets its own rule for what counts as a view, so compare views within one network, not across networks. Category: Metrics. Source: https://developers.facebook.com/docs/instagram-platform/reference/instagram-media/insights ## W ### Watch time The total time people spent watching a video. Platforms use it alongside views to judge whether a video holds attention. Category: Metrics ### Webhook An HTTP request a service sends to your URL when something happens, such as a post publishing or failing, so your code reacts without polling. Category: Developer. Source: https://postboost.co/docs/webhooks ### Webhook signature An HMAC of the request body, made with a secret you share with the sender, so you can check a webhook really came from it. Compute it over the raw body and compare in constant time. Category: Developer. Source: https://postboost.co/docs/webhooks/#verifying-signatures ### Weighted characters How X counts toward its 280-character limit for standard accounts: most characters count as 1, but every link counts as 23 and every emoji as 2. Category: Content. Source: https://docs.x.com/resources/fundamentals/counting-characters ## Y ### YouTube Shorts YouTube's vertical short-video format, shown in the Shorts feed alongside regular long videos on a channel. Category: Platforms Social media has its own vocabulary, and much of it means slightly different things on each network. Reach and impressions are not the same number. Engagement rate changes depending on whether you divide by followers or by reach. Instagram now caps hashtags at 5, Threads counts emoji by their bytes and Bluesky counts graphemes. Then there is the developer side, from webhooks and rate limits to idempotency keys and MCP servers, which matters as soon as you automate posting or let an AI agent help. This glossary explains more than 110 of those terms in plain language. Each definition is our own wording, kept to one to three sentences. Where a definition gives a number or a platform rule, it cites the platform's own documentation or a dated news report, so you can check it yourself. We review the list regularly and show the date it was last verified at the top of the page. Use the search box to find a term, or filter by category: - **Metrics**: what analytics numbers mean and how to compare them. - **Content**: the parts of a post, from captions and hashtags to aspect ratios and link previews. - **Ads**: the paid side, from CPM and ROAS to retargeting. - **Platforms**: how each network works and what its features are called. - **Developer**: APIs, tokens, webhooks and the protocols behind automation and AI agents. - **Strategy**: planning, scheduling, approvals and working with creators. Many entries link to a free tool that does the job for you, such as the engagement rate calculator, the UTM builder or the character counter, and to a /learn guide that goes deeper. Every term has its own anchor, so you can link straight to a definition, for example `#engagement-rate`. The glossary is also available as JSON from the free PostBoost API and as the `get-glossary` tool on our MCP server, so your scripts and AI assistants can look up a term the same way. ## How to use 1. Type a word in the search box to show only the terms whose name or definition contains it. 2. Pick a category, such as Metrics or Developer, to narrow the list; pick All to see every term again. 3. Open a term's guide, tool or source link to go deeper or check the platform rule yourself. 4. Copy a term's link (the # next to it) to send someone straight to that definition. ## FAQ ### What is the difference between reach and impressions? Reach counts the unique accounts that saw a post; impressions count every time it was shown, including repeat views by the same person. Meta's API no longer reports impressions for Instagram posts created after 2 July 2024, so check which number your report uses. ### How is engagement rate calculated? Divide a post's engagements (likes, comments, shares, saves) by an audience number and multiply by 100. The audience can be followers, reach or impressions; pick one and use it in every report, because the results differ a lot. ### Where do these definitions come from? We write every definition in our own words. When one states a platform rule or a number, it cites the platform's documentation or a dated news report, listed with the term. ### Can I use the glossary from code or an AI assistant? Yes. The same terms are on the free PostBoost API and on our MCP server as `get-glossary`, and you can filter by search text or category. ### Can I link to a single term? Yes. Every term has an anchor, for example `/tools/social-media-glossary#engagement-rate`, that scrolls straight to it. ## Related - [Engagement rate calculator for Instagram, TikTok and LinkedIn](https://postboost.co/tools/engagement-rate-calculator): Calculate engagement rate by followers, reach or impressions, for one post or several. See the formula with your own numbers. Free, in your browser. - [UTM builder for social media links](https://postboost.co/tools/utm-builder): Build UTM-tagged links for social posts in your browser: network presets, live preview, naming warnings and saved presets. Free, no signup. - [Social media character counter](https://postboost.co/tools/social-media-character-counter): Free character counter for X, Threads, Bluesky, Instagram, LinkedIn, TikTok and more. Counts as each network does, live in your browser. - [Engagement Rate by Reach vs Followers: Which to Use](https://postboost.co/learn/engagement-rate-reach-vs-followers): Engagement rate by reach or by followers? See what each method answers, worked examples with the same posts, the multi-post trap and how to report it. - [Analytics](https://postboost.co/features/analytics): Account and post analytics for your social accounts in one place, and reports you can download as CSV or a branded PDF. Canonical: https://postboost.co/tools/social-media-glossary