# SEO basics per Google documentation

German title: SEO-Grundlagen nach Google-Dokumentation

> According to Google documentation, crawlable links, a sitemap as a hint, canonical signals, structured data matching visible content and, for JavaScript pages, server-side or pre-rendering matter. robots.txt controls crawling, not indexing. Specifics for knowledge portals are not verified.

## Facts

- **Sitemap:** hint, not a guarantee; 50 MB / 50,000 URLs
- **Canonical:** strong signal, not a directive
- **Structured data:** JSON-LD recommended
- **robots.txt:** controls crawling, not indexing
- **JavaScript:** server-side or pre-rendering recommended

## Checklist with evidence

Basics and Google sourceBuilding block What Google documents
Links a elements with href ; link important pages from at least one other page
Sitemap A hint, not a guarantee; up to 50 MB (uncompressed) or 50,000 URLs per file
Canonical strong signal, not a directive; redirects are stronger than rel=canonical
Structured data JSON-LD recommended; must match visible content; does not guarantee rich results
JavaScript Server-side or pre-rendering recommended; Google renders with headless Chromium
robots.txt / noindex robots.txt controls crawling, not indexing; use noindex or password protection for that

## Separating crawling from indexing

- robots.txt tells crawlers which URLs they may access and mainly serves to avoid overloading servers and crawling unimportant or duplicate pages.
- A blocked URL can still appear in search results, for example when other pages link to it. To reliably keep a page out, Google names noindex or password protection.
- robots.txt is not a protection mechanism; reputable crawlers follow it, others may not.

## JavaScript pages

- Server-side or pre-rendering makes the site faster for users and crawlers; according to Google, not all bots can run JavaScript either.
- Do not use fragments ( # ) to load different content; use the History API with real paths instead.
- Soft 404: in client-side rendered apps an error page can be handled by a JavaScript redirect to a URL that returns a 404 status, or by adding a noindex via JavaScript.
- If Google encounters noindex, it may skip rendering and JavaScript execution. Removing noindex via JavaScript may therefore not work; a page meant to be indexed should not contain noindex in the original code.

## Not verified

There is no primary source on specifics of knowledge portals; the report covers the general Google basics. Whether statically served pages meet all requirements depends on the individual implementation and is not verified here.

## Sources

- Google Search Central: SEO link best practices (primary source)
- Google Search Central: Build and submit a sitemap (primary source)
- Google Search Central: Specify a canonical URL (primary source)
- Google Search Central: Intro to structured data (primary source)
- Google Search Central: JavaScript SEO basics (primary source)
- Google Search Central: Introduction to robots.txt (primary source)

Checked on: 24 October 2026.

## Questions

### Do I need a sitemap?

Not necessarily. It is a hint to Google, not a guarantee.

### Are single-page apps bad for SEO?

Google can render JavaScript but recommends server-side or pre-rendering. Typical pitfalls are soft-404 pages and fragment URLs instead of real paths.

### Is structured data mandatory?

No. They do not guarantee rich results and must match the visible content.

### Does robots.txt keep a page out of Google?

No. A blocked URL can still appear. noindex or password protection does that reliably.

### Does this apply specifically to knowledge portals?

These are general Google basics. There is no primary source specific to knowledge portals.

## Related

- [Technical SEO: fundamentals](https://munichmedia.com/reports/technisches-seo-grundlagen.md)
- [On-page SEO & content structure](https://munichmedia.com/reports/onpage-seo-content-struktur.md)
- [Internal linking & topic silos](https://munichmedia.com/reports/interne-verlinkung-themen-silos.md)
- [Core Web Vitals & performance](https://munichmedia.com/reports/core-web-vitals-performance.md)

Canonical HTML: https://munichmedia.com/reports/seo-basics-fuer-wissensportale