Technical SEO for modern sites

Three prerequisites

Crawl access. A directives file that doesn't block, an up-to-date sitemap, and real internal links. A page reached only through a click that runs code isn't always found.

Content in the markup. If the main content is painted only after long execution in the browser, relying on the engine to run it is a gamble. Serve the important content in the first response.

One address per page. The same content at several addresses splits signals. Declare the preferred address.

What actually helps

A unique title and description per page, a logical heading structure, descriptive link text instead of “click here,” and structured data where it has meaning — product, article, questions and answers.

Speed and layout stability enter here too, but as a secondary consideration to content that answers what was searched.

What harms

Near-identical pages in bulk, text written for the engine and not the person, and routes broken after a structure change. On any address change — a permanent redirect from old to new, or you erase years of signals.