Complete explanation of all recommendations: what it is, why it matters and how to do it.
The site must run on HTTPS with a valid certificate.
The page must return a 200 code and be reliably available.
Every page needs a unique, descriptive title of 50–60 characters.
A short page description (120–158 characters) shown under the title in results.
Keywords in <meta name="keywords">. Google ignores them, Seznam.cz may consider them.
Exactly one H1 and a logical hierarchy of subheadings.
Images need an alt description, a modern format, and compression.
The meta viewport ensures correct display on mobile.
The lang attribute on <html> specifies the page language.
Tells search engines which version of a URL is the main one.
Controls what search engines may crawl and index.
Controls how a link looks when shared on Facebook, LinkedIn, etc.
Link preview on the X (Twitter) platform.
Machine-readable markup that unlocks rich results.
Speed is both a ranking factor and a key UX element.
Working links and meaningful internal linking.
The site's icon in the tab and in mobile results.
Short, readable, and logical addresses with keywords.
Sufficiently comprehensive, readable, and unique content.
A synchronous <script> blocks rendering, so defer it.
CSS and JS in the head that delay the first render.
Large CSS in the head delays rendering.
Without compression, an unnecessarily large amount of data is transferred.
Compression is not active, so enable Gzip/Brotli.
Static files should be stored at the visitor's end.
Load off-screen images only when scrolling.
WebP and AVIF are 25–50% smaller than JPEG/PNG.
The time before the server sends the first byte of the response.
A page that's too large loads slowly.
The page is large, so lighten it.
Many files = many requests = a slower start.
Combine and minify styles.
Large JS delays and burdens the device's CPU.
Too many HTML elements slow down rendering.
The element count exceeds a reasonable limit.
Lots of style="..." worsens caching and maintainability.
Many <script>s directly in the HTML block and can't be cached.
Without image dimensions, the layout jumps (CLS).
Important resources can be loaded earlier via rel="preload".
HTTP/2 and HTTP/3 are faster than the old HTTP/1.1.
Never prevent the user from zooming the page.
Body text at least 16px, fine print at least 12px.
Clickable elements must be readable and easy to hit.
Prefer rem/em over fixed px for font sizes.
Text must have sufficient contrast (WCAG AA 4.5:1).
Images must fit on mobile without horizontal scrolling.
A list of URLs for search engines that helps faster indexing.
How the page looks in Google's results.
Tells Google which language version belongs to which audience.
Google primarily evaluates the mobile version (mobile-first).
HTTPS, security headers, and protecting visitors.
Short 301 chains, no loops.
An overview of the site's CMS, frameworks, and libraries.
A site usable even by people with disabilities.
Cookie consent and personal data protection.
Correct DNS records and a valid SSL certificate.
Links leading to a 404 spoil both UX and the crawl.
So that ChatGPT, Gemini, Perplexity, and others cite you.