Technical SEO lets a search engine find and read your site without trouble. However good the content, a page does not appear if there is a crawling or indexing problem.
Crawling and indexing
A search bot crawls pages and indexes content. Places that can cause problems:
- robots.txt: May be blocking an important section by mistake.
- noindex tag: Keeps a page out of search; use only on purpose.
- Sitemap: Lists all important pages; submit it to Search Console.
- Broken links and 404s: Lower crawl efficiency.
Canonical URL
If the same content is reachable at several addresses, declare the main one with a canonical tag. On a multilingual site hreflang is also needed; see how to build a multilingual website.
Redirects
Moved pages should redirect with 301; see the 301 redirects guide.
Speed and mobile
Page speed and mobile-friendliness are ranking signals; see Core Web Vitals.
https and security
The whole site should be on https; see why you need an SSL certificate.
Structured data
Markup that tells the search engine clearly about the business, services, FAQs and articles.
Monitoring
Check the coverage and crawl reports in Google Search Console regularly; see measuring with Analytics and Search Console.
We do these from the start when a site is built: web design and SEO. An example of a multilingual yacht site: Cordelia Yachting. For the general frame see what is SEO and how does it work.