SEO Glossary
40 terms explained
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A
Alt Text
Alternative text set via an image’s alt attribute. It describes the image for screen readers and search engines and is shown if the image fails to load — important for accessibility and image SEO.
Anchor Text
The visible, clickable words in a hyperlink. Descriptive anchor text helps users and search engines understand what the linked page is about.
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C
Canonical URL
The preferred version of a web page that search engines should index when multiple URLs have similar or duplicate content. Specified using the rel="canonical" link element.
Crawl Budget
The number of pages a search engine will crawl on a site within a given timeframe. Efficient site structure and internal linking help important pages get crawled.
Click-Through Rate (CTR)
The percentage of people who click a result after seeing it. In search, compelling title tags and meta descriptions raise organic CTR.
Core Web Vitals
A set of Google metrics measuring real-world user experience: loading (LCP), interactivity (INP), and visual stability (CLS). They are a ranking factor.
Cumulative Layout Shift (CLS)
A Core Web Vital that quantifies unexpected layout movement during loading. A good CLS score is below 0.1.
CDN
A Content Delivery Network — a geographically distributed set of servers that cache and serve content from locations close to users, reducing latency.
D
Domain Authority
A third-party score (popularized by Moz) that predicts how well a domain may rank, based largely on its backlink profile. It is not an official Google metric.
Duplicate Content
Substantively identical content available at more than one URL. It can split ranking signals; canonical tags and redirects help consolidate them.
DNS
The Domain Name System translates human-readable domain names (example.com) into the IP addresses servers use to route traffic.
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F
H
I
Internal Linking
Links from one page on a site to another page on the same site. Internal links help users navigate, spread link equity, and help search engines discover and rank pages.
Indexing
The process by which a search engine stores and organizes pages it has crawled so they can appear in search results. A page must be indexed before it can rank.
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K
L
Long-Tail Keyword
A longer, more specific search phrase (usually 3+ words) with lower search volume but higher intent and less competition than broad head terms.
Largest Contentful Paint (LCP)
A Core Web Vital that measures how long the largest visible element takes to render. A good LCP is under 2.5 seconds.
M
Meta Tags
HTML elements that provide metadata about a web page to search engines and browsers. Common meta tags include title, description, and robots directives.
Meta Description
A short HTML summary (ideally 150-160 characters) of a page’s content. Google often shows it as the snippet under the title in search results, influencing click-through rate.
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O
Open Graph
A protocol developed by Facebook that enables web pages to become rich objects in a social graph, controlling how content appears when shared on social media.
Organic Traffic
Visitors who arrive at a website through unpaid search engine results, as opposed to paid ads, referrals, or direct visits.
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R
Robots.txt
A text file placed in the root directory of a website that tells search engine crawlers which pages or sections they can or cannot access.
Robots Meta Tag
An HTML meta tag (e.g. <meta name="robots" content="noindex">) that gives per-page crawling and indexing directives to search engines.
Ranking
The position a page occupies in search results for a given query. Higher rankings generally earn far more clicks and organic traffic.
Responsive Design
A design approach where a layout adapts fluidly to any screen size. It is essential for mobile usability and mobile-first indexing.
S
Structured Data
A standardized format (usually JSON-LD) that helps search engines understand the content and context of a web page, enabling rich snippets in search results.
Schema Markup
A vocabulary of tags (microdata) that you can add to your HTML to improve how search engines read and represent your page in SERPs.
Sitemap
An XML file that lists all important pages of a website, helping search engines discover and crawl your content more efficiently.
SERP
Search Engine Results Page - the page displayed by a search engine in response to a query, containing organic results, ads, and featured snippets.
SSL Certificate
A digital certificate that enables HTTPS by encrypting traffic between a browser and server. Browsers flag sites without it as “Not secure.”
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Learn More
Want to dive deeper into SEO concepts? Check out these resources: