Glossary
SEO: terms A–Z
Every SEO term explained in plain English — keywords, backlinks, crawling, indexing, SERP, and more.
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SEO has a reputation for jargon. This page cuts through it. Every term is explained the way you'd explain it to a smart friend who doesn't work in marketing.
Quick summary
This page covers 60+ SEO terms from A to Z. For full SEO guides, visit the SEO section. Use Ctrl+F / Cmd+F to jump to any term.
A–C
| Term | Plain-English definition |
|---|---|
| Algorithm | The set of rules search engines use to decide which pages to show for a given search query — and in what order. Google's algorithm is constantly updated. |
| Alt text | A text description of an image. Helps visually impaired users and tells search engines what the image shows. See Image SEO & alt text. |
| Anchor text | The clickable, visible text of a hyperlink. E.g. in "read our SEO guide," the anchor text is "SEO guide." |
| Authority | A measure of how trustworthy and credible a website is in the eyes of search engines. Built through quality content and backlinks. |
| Backlink | A link from another website pointing to yours. Quality backlinks from reputable sites boost your authority. See Backlinks, explained. |
| Black hat SEO | Tactics that try to game search engine rankings through deception or manipulation. Against Google's guidelines and can result in penalties. |
| Bounce rate | The percentage of visitors who leave your site after viewing only one page. High bounce rates may indicate the page isn't meeting visitor expectations. |
| Breadcrumbs | Navigation links showing a visitor's location within a site hierarchy (e.g. Home > Blog > SEO). Also a structured data markup that appears in search results. |
| Canonical URL | The "official" version of a page when multiple URLs could show the same content. Prevents duplicate content issues. |
| Click-through rate (CTR) | The percentage of people who click your search result listing compared to how many see it. Higher CTR usually comes from compelling titles and meta descriptions. |
| Crawl | What search engine bots do when they follow links around the web and read page content to index it. |
| Crawl budget | The number of pages a search engine will crawl on your site in a given period. Large sites with many low-quality pages can waste their crawl budget. |
D–I
| Term | Plain-English definition |
|---|---|
| De-indexing | The removal of a page from search engine results. Can be accidental (noindex tag) or a penalty. |
| Domain authority (DA) | A score (0–100) created by Moz predicting how well a domain will rank. Not a Google metric, but a useful third-party benchmark. |
| Duplicate content | Substantially identical content appearing at multiple URLs. Can confuse search engines about which page to rank. |
| E-E-A-T | Experience, Expertise, Authoritativeness, Trustworthiness. The framework Google uses to evaluate content quality and credibility. |
| Featured snippet | A special result box at the top of Google search that directly answers a query, pulled from a web page. Also called "position zero." |
| Google Business Profile | Google's free business listing that appears in map results and local searches. See Google Business Profile for SEO. |
| Google Search Console | Google's free tool that shows how your site performs in search — clicks, impressions, indexing issues. See What is Google Search Console?. |
| Heading tags | HTML tags (H1, H2, H3…) that mark up headings in page content. H1 is the page's main title. Important for both readability and SEO. See Headings & content structure for SEO. |
| Impression | One instance of your page appearing in search results, whether or not anyone clicks on it. |
| Index | The search engine's database of web pages. If a page is "indexed," it can appear in search results. |
| Internal link | A link from one page on your site to another page on the same site. Helps search engines understand your site structure. See Internal linking explained. |
J–O
| Term | Plain-English definition |
|---|---|
| Keyword | A word or phrase people type into search engines. Optimizing for relevant keywords helps you appear when they search. See Keywords, explained. |
| Keyword density | How often a keyword appears on a page relative to total word count. Less important today than it used to be — focus on relevance, not repetition. |
| Keyword research | The process of finding which words and phrases your potential customers search for. See Keyword research basics. |
| Keyword stuffing | Overloading a page with keywords in an unnatural way. Ineffective and penalized by Google. |
| Knowledge panel | The information box that sometimes appears on the right side of Google results, showing key facts about a business, person, or topic. |
| Link building | The practice of earning or acquiring backlinks from other websites to improve your authority. |
| Local SEO | Optimizing your website to appear in search results for geographically relevant queries — "plumber in Chicago." See Local SEO basics. |
| Long-tail keyword | A longer, more specific search phrase — "best accountant for freelancers in Seattle" vs. just "accountant." Less competitive, often higher purchase intent. |
| Meta description | A short summary of a page shown in search results beneath the title. Doesn't directly affect ranking but affects click-through rate. See Page titles & meta descriptions. |
| Mobile-first indexing | Google primarily uses the mobile version of a page for indexing and ranking. See Mobile-friendliness & SEO. |
| Noindex | An instruction telling search engines not to include a page in their index. Used for private, duplicate, or low-value pages. |
P–R
| Term | Plain-English definition |
|---|---|
| On-page SEO | Optimization done directly on your page — titles, headings, content, images, internal links, URL. See On-page SEO explained. |
| Off-page SEO | Optimization outside your website — backlinks, social signals, brand mentions. |
| Organic search | Unpaid search results. Visitors that arrive via organic search found you naturally, not through an ad. |
| Page title | The HTML title of a page, shown in browser tabs and as the blue link in search results. One of the most important on-page SEO elements. |
| PageRank | Google's original algorithm for ranking pages based on the quantity and quality of inbound links. Still a factor, though one of hundreds. |
| Penalty | A ranking demotion from Google, either from an algorithm update or manual action, usually due to policy violations. |
| Position | Where your page appears in search results — position 1 is the first organic result. |
| Redirect | Sending visitors (and search engines) from one URL to another. A 301 redirect passes SEO value to the destination. |
| Rich results | Enhanced search listings with additional visual elements — star ratings, FAQs, event dates, recipes. Enabled by structured data markup. |
| Robots.txt | A file that tells search engine crawlers which pages or sections of your site not to crawl. See Sitemaps & robots.txt explained. |
S–Z
| Term | Plain-English definition |
|---|---|
| Schema markup | Code added to pages that helps search engines understand the content — business info, reviews, events, FAQs. Enables rich results. |
| Search engine | A system for finding web pages — Google, Bing, DuckDuckGo. |
| SERP | Search Engine Results Page. The page you see after typing a query into a search engine. |
| Sitemap | An XML file listing all your site's pages, helping search engines discover and index them. See Sitemaps & robots.txt explained. |
| Slug | The URL-friendly text in a page address. Good slugs are short, descriptive, and keyword-relevant. |
| SSL/HTTPS | Having HTTPS is a minor Google ranking factor. More importantly, browsers warn users on HTTP sites. |
| Structured data | See Schema markup. |
| Technical SEO | Behind-the-scenes optimization — site speed, crawlability, indexing, mobile-friendliness, HTTPS. See Technical SEO basics. |
| Title tag | See Page title. |
| White hat SEO | Ethical, guideline-compliant SEO tactics focused on providing genuine value. The only approach worth taking. |
Common questions
Related guides
- What is SEO?
- How search engines work
- Keywords, explained
- On-page SEO explained
- SEO terms, explained simply
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