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30 terms

The SEO glossary, in plain English

Definitions of the SEO terms that actually matter — canonical, Core Web Vitals, crawl budget, JSON-LD and more. Tap any term for the full explanation.

Alt text
A text description of an image, read by screen readers and used by search engines to understand what the image shows.
Anchor text
The clickable text of a link — descriptive wording helps search engines and users understand where the link leads.
Backlink
A link from another website to yours — high-quality backlinks remain one of the strongest ranking signals.
Canonical URL
A tag that tells search engines which version of a duplicate or similar page is the master version to index.
CLS (Cumulative Layout Shift)
A Core Web Vital measuring unexpected layout movement while a page loads — aim for a score under 0.1.
Core Web Vitals
Google's set of user-experience metrics — LCP, CLS, and INP — that feed directly into rankings.
Crawl budget
The number of pages a search engine will crawl on your site in a given window — wasting it on junk URLs hurts indexing.
Crawlability
How easily search engine bots can reach and navigate the pages on your site.
E-E-A-T
Experience, Expertise, Authoritativeness, and Trust — the quality signals Google's raters use to judge content.
Hreflang
An attribute telling Google which language and region a page targets, for multilingual or multi-regional sites.
Indexing
The process of a search engine storing a page so it can appear in results — crawling and indexing are not the same thing.
INP (Interaction to Next Paint)
A Core Web Vital measuring how quickly a page responds to user input — it replaced FID in 2024. Aim for under 200ms.
JSON-LD
Google's recommended format for structured data — a script block that describes your content to enable rich results.
Keyword cannibalization
When multiple pages target the same keyword and compete with each other, weakening all of them in search.
LCP (Largest Contentful Paint)
A Core Web Vital measuring how fast the largest visible element renders — aim for under 2.5 seconds.
Meta description
The summary shown under your title in search results — it doesn't rank pages but heavily influences click-through rate.
noindex
A directive telling search engines not to show a page in results — the page can still be crawled.
nofollow
A link attribute telling search engines not to pass ranking authority through that link.
Open Graph
Meta tags that control how your page looks when shared on social media — title, description, and preview image.
Organic traffic
Visitors who arrive from unpaid search engine results rather than ads, social, or direct links.
Rich results
Enhanced search listings — star ratings, FAQs, images, prices — that structured data makes eligible in the SERP.
Robots.txt
A file at your site root that tells crawlers which URLs they may or may not request.
Schema markup
Structured data, usually written in JSON-LD, that labels your content type so search engines can parse it precisely.
SERP
Search Engine Results Page — the page of results a search engine returns for a query.
Sitemap (XML)
A file listing your important URLs to help search engines discover and prioritize crawling them.
Structured data
Machine-readable markup that describes your content so search engines can understand and enhance it.
Title tag
The clickable headline in search results and browser tabs — the single strongest on-page signal. Aim for 50–60 characters.
TTFB (Time to First Byte)
The time from a request to the first byte of the server's response — a slow TTFB delays everything after it, including LCP.
Canonicalization
The process of choosing the single preferred URL when several addresses serve the same or near-identical content.
Crawl-delay
A robots.txt directive asking bots to wait a set interval between requests, to reduce server load.

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