The SEO glossary
Plain-English definitions of the terms worth knowing, with a worked example for each and the evidence attached where evidence exists. 20 terms and counting.
SEO basics
Keyword difficulty
Keyword difficulty is a score estimating how hard it is to rank on page one for a keyword.
SERP (search engine results page)
A SERP is the page of results Google returns for a query, including organic links and features like snippets and AI Overviews.
On-page & content
Keyword cannibalization
Keyword cannibalization is two or more of your own pages competing for the same query.
Meta description
The meta description is the short summary Google may show under a result's title.
Title tag
The title tag is the HTML element that sets a page's title, shown as the clickable headline in search results.
Technical SEO
Canonical tag
A canonical tag tells search engines which URL is the master version of duplicate or similar pages.
Crawl budget
Crawl budget is how many pages Googlebot will crawl on your site in a given period.
Crawlability
Crawlability is how easily search engines can reach and read the pages on your site.
Hreflang
Hreflang tags tell Google which language and region each version of a page is meant for.
Indexing
Indexing is Google storing a page in its database so it can appear in search results.
Structured data
Structured data is code (usually schema.org) that labels what your content means so search engines can understand and enrich it.
Technical SEO
Technical SEO is the work of making a site easy for search engines to crawl, render and index.
Links & authority
Anchor text
Anchor text is the visible, clickable words in a link.
Nofollow link
A nofollow link carries a rel="nofollow" attribute telling Google not to pass ranking credit through it.
Off-page SEO
Off-page SEO is everything you do beyond your own pages to build authority and trust, chiefly earning links and mentions.
Page authority
Page authority is a third-party score predicting how well a single page will rank, based mainly on its links.
PageRank
PageRank is Google's original algorithm for scoring a page's importance by the links pointing to it.
Measurement
Bounce rate
Bounce rate is the share of visits where someone views one page and leaves without another interaction.
Dwell time
Dwell time is how long a searcher stays on your page before returning to the search results.
Organic traffic
Organic traffic is the visitors who reach your site by clicking an unpaid search result.
Missing a term you'd expect to find? Tell me and I'll add it: use the contact form. For the studies behind these definitions, see the research library.