SEO Glossary
A plain-English guide to the most important SEO terms. Click any term for more detail where available.
| Term | Definition |
|---|---|
| Alt Text | Text description of an image for accessibility and SEO. |
| Anchor Text | The clickable text of a hyperlink. |
| Backlink | A link from another website to yours. A key ranking factor. |
| Bounce Rate | Percentage of visitors who leave after viewing only one page. |
| Broken Link | A link that leads to a page that no longer exists (404 error). |
| Canonical URL | The preferred version of a page when multiple URLs have the same content. |
| CLS | Cumulative Layout Shift — a Core Web Vital measuring visual stability. |
| Core Web Vitals | Google's metrics for page experience: LCP, INP, and CLS. |
| Crawl Budget | The number of pages a search engine will crawl on your site in a given time. |
| Crawling | The process of search engine bots visiting and reading web pages. |
| Domain Authority | A score (1-100) predicting a site's ability to rank. Created by Moz. |
| E-E-A-T | Experience, Expertise, Authoritativeness, Trustworthiness — Google's quality framework. |
| Featured Snippet | A highlighted answer box at the top of Google results. |
| H1 Tag | The main heading of a page. Should be unique and contain the primary keyword. |
| Indexing | The process of adding a page to a search engine's database. |
| Internal Link | A link from one page on your site to another page on the same site. |
| Keyword Density | The percentage of times a keyword appears relative to total word count. |
| Keyword Research | The process of finding words people search for related to your content. |
| LCP | Largest Contentful Paint — a Core Web Vital measuring loading speed. |
| Lazy Loading | Deferring image loading until the user scrolls near them. |
| Link Equity | The ranking value passed from one page to another through links. |
| Long-Tail Keyword | A specific, multi-word search phrase with lower volume but higher intent. |
| Meta Description | The HTML tag that provides a summary of the page for search results. |
| Meta Tags | HTML tags that provide metadata about a page to search engines. |
| Nofollow | A link attribute telling search engines not to pass ranking value. |
| Noindex | A directive telling search engines not to include a page in their index. |
| On-Page SEO | Optimising individual web pages for search engines (content + HTML). |
| Open Graph | Meta tags controlling how pages appear when shared on social media. |
| Organic Traffic | Visitors who arrive at your site from unpaid search results. |
| PageRank | Google's algorithm for measuring page importance based on links. |
| Readability | How easy content is to read, measured by scores like Flesch-Kincaid. |
| Redirect (301) | A permanent redirect from one URL to another. |
| Robots.txt | A file telling search engine crawlers which pages to access. |
| Schema Markup | Structured data code that helps search engines understand content. |
| SEM | Search Engine Marketing — paid advertising in search results. |
| SERP | Search Engine Results Page — the page of results Google shows. |
| SERP Snippet | The title, URL, and description shown for a result in search. |
| Sitemap | An XML file listing all pages you want search engines to index. |
| Title Tag | The HTML tag defining the page title shown in search results and browser tabs. |
| Thin Content | Pages with very little useful content, typically under 300 words. |
For a complete walkthrough, see the SEO for beginners guide or run a free SEO audit.
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Last updated: March 2026