SEO Library
Technical SEO — SEO terms explained
51 SEO and marketing concepts explained in plain English — what each one means, why it matters, how to apply it and the mistakes to avoid.
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Technical SEO
301 Redirect
A 301 redirect is a permanent redirect that sends users and search engines from one URL to another and signals that the…
Technical SEO
404 Error
A 404 error is the HTTP status a server returns when a requested page doesn't exist. Some 404s are normal; 404s on…
Technical SEO
404 Error
A 404 error is the HTTP status a server returns when a requested page doesn't exist. Some 404s are normal; 404s on…
A
Technical SEO
AMP (Accelerated Mobile Pages)
AMP is an open-source framework for building fast mobile pages. It was once required for some Google features, but that is no…
Technical SEO
AMP (Accelerated Mobile Pages)
AMP is an open-source framework for building fast mobile pages. It was once required for some Google features, but that is no…
C
Technical SEO
Canonical Tag
A canonical tag (rel="canonical") is an HTML element that tells search engines which URL is the preferred version of a page when…
Technical SEO
Cloaking
Cloaking is showing different content or URLs to search engines than to human visitors in order to manipulate rankings. It violates Google's…
Technical SEO
Core Web Vitals
Core Web Vitals are three Google metrics that measure real-user page experience: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and…
Technical SEO
Crawl Budget
Crawl budget is the number of URLs a search engine is willing and able to crawl on your site in a given…
Technical SEO
Crawlability
Crawlability is how easily search engine bots can discover and access the pages on your website through links, sitemaps and accessible server…
Technical SEO
Cumulative Layout Shift (CLS)
Cumulative Layout Shift (CLS) is a Core Web Vital that measures how much visible content unexpectedly moves while a page is in…
Technical SEO
Cumulative Layout Shift (CLS)
Cumulative Layout Shift (CLS) is a Core Web Vital that measures how much visible content unexpectedly moves while a page is in…
D
Technical SEO
Duplicate Content
Duplicate content is identical or very similar content that appears at more than one URL, on the same site or across different…
Technical SEO
Duplicate Content
Duplicate content is identical or very similar content that appears at more than one URL, on the same site or across different…
F
Technical SEO
Faceted Navigation
Faceted navigation lets users filter listings by attributes like size, colour, brand or price. It's great for shoppers but can create huge…
Technical SEO
First Contentful Paint (FCP)
First Contentful Paint measures when the browser first renders any text or image from the page. It's a supporting speed metric (not…
Technical SEO
First Contentful Paint (FCP)
First Contentful Paint measures when the browser first renders any text or image from the page. It's a supporting speed metric (not…
H
Technical SEO
Hreflang
Hreflang is an HTML attribute that tells search engines which language and regional version of a page to show to users, so…
Technical SEO
HTTP Status Codes
HTTP status codes are three-digit responses a server sends for every request, telling browsers and crawlers whether a page loaded (200), moved…
Technical SEO
HTTPS
HTTPS is the secure version of HTTP: data between the browser and the website is encrypted using TLS. It's a lightweight Google…
I
Technical SEO
Index Bloat
Index bloat happens when search engines index many low-value URLs — tag archives, filters, internal search pages, thin or duplicate pages —…
Technical SEO
Interaction to Next Paint (INP)
Interaction to Next Paint is a Core Web Vital measuring how quickly a page visually responds to user interactions like taps, clicks…
J
Technical SEO
JavaScript SEO
JavaScript SEO is the practice of making sure search engines can crawl, render and index content that depends on JavaScript — common…
Technical SEO
JSON-LD
JSON-LD (JavaScript Object Notation for Linked Data) is the format Google recommends for adding structured data to web pages. It sits in…
L
Technical SEO
Largest Contentful Paint (LCP)
Largest Contentful Paint (LCP) is a Core Web Vital that measures when the largest image or text block in the viewport finishes…
Technical SEO
Largest Contentful Paint (LCP)
Largest Contentful Paint (LCP) is a Core Web Vital that measures when the largest image or text block in the viewport finishes…
M
Technical SEO
Meta Robots Tag
The meta robots tag is an HTML element in the page head that tells search engines how to index the page and…
Technical SEO
Meta Robots Tag
The meta robots tag is an HTML element in the page head that tells search engines how to index the page and…
Technical SEO
Mobile-First Indexing
Mobile-first indexing means Google predominantly uses the mobile version of a page's content for indexing and ranking. Since 2023 it applies to…
P
Technical SEO
Page Speed
Page speed is how quickly a web page loads and becomes usable. Google measures real-user speed mainly through Core Web Vitals; faster…
Technical SEO
Pagination
Pagination splits long lists of content — blog archives, product categories, forum threads — across numbered pages (page 1, 2, 3…). Done…
Technical SEO
Pagination
Pagination splits long lists of content — blog archives, product categories, forum threads — across numbered pages (page 1, 2, 3…). Done…
R
Technical SEO
Redirect Chain
A redirect chain happens when a URL redirects to another URL that redirects again before reaching the final page (A → B…
Technical SEO
Rich Results
Rich results are enhanced search listings that show extra information — star ratings, prices, availability, breadcrumbs, event dates, recipe times or video…
Technical SEO
Robots.txt
Robots.txt is a plain-text file at the root of a website that tells search engine crawlers which URLs they may or may…
S
Technical SEO
Soft 404
A soft 404 is a page that tells users it doesn't exist (or has almost no content) but returns a 200 OK…
Technical SEO
Soft 404
A soft 404 is a page that tells users it doesn't exist (or has almost no content) but returns a 200 OK…
Technical SEO
Structured Data (Schema Markup)
Structured data is standardised code — usually JSON-LD using the Schema.org vocabulary — that describes a page's content to search engines, such…
T
Technical SEO
Technical SEO
Technical SEO is the work that makes a website easy for search engines to crawl, render, index and understand — covering site…
Technical SEO
Technical SEO
Technical SEO is the work that makes a website easy for search engines to crawl, render, index and understand — covering site…
Technical SEO
Time to First Byte (TTFB)
Time to First Byte (TTFB) measures how long it takes from a browser's request until the first byte of the response arrives.…
Technical SEO
Time to First Byte (TTFB)
Time to First Byte (TTFB) measures how long it takes from a browser's request until the first byte of the response arrives.…
X
Technical SEO
X-Robots-Tag
The X-Robots-Tag is an HTTP response header that gives search engines indexing instructions — like noindex or nofollow — for any file…
Technical SEO
X-Robots-Tag
The X-Robots-Tag is an HTTP response header that gives search engines indexing instructions — like noindex or nofollow — for any file…
Technical SEO
XML Sitemap
An XML sitemap is a file that lists the URLs you want search engines to crawl and index, often with the date…
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