What Is Technical SEO?
The crawling, rendering and indexing layer that decides whether content gets a chance at all.
What is technical SEO?
Technical SEO covers everything affecting whether search engines can find, crawl, render, understand and index a site: URL structure, canonical tags, robots directives, sitemaps, redirects, JavaScript rendering, structured data, speed and internal linking. It does not create demand, but without it good content may never be seen.
Technical SEO problems are usually a short list of specific faults rather than a long list of small ones. One misplaced directive can remove an entire section from search results, and it is often invisible until someone looks.
How do I know if I have technical SEO problems?
Compare how many pages you expect to be indexed with what Search Console's index coverage report shows. A large unexplained gap is the clearest signal. Also check whether important pages appear when you search for their exact title in quotation marks.
Sudden drops in index coverage usually follow a deployment. Correlating the date of the drop with your release history identifies the cause quickly.
What is a canonical tag?
A canonical tag tells search engines which URL is the preferred version when the same or similar content is reachable at several addresses. Used correctly it consolidates signals. Used wrongly — for example pointing every page at the homepage — it removes pages from search results entirely.
Canonical problems are common after platform migrations and theme changes, and they are silent: nothing appears broken to a visitor.
What does robots.txt actually do?
It requests that crawlers avoid certain paths. It does not prevent indexing on its own, and it does not hide anything from people. Blocking CSS and JavaScript files is a common mistake, because it stops search engines rendering pages the way visitors see them.
To keep a page out of the index, use a noindex directive and allow crawling so it can be read. Blocking a page in robots.txt can prevent the noindex from ever being seen.
Does JavaScript hurt SEO?
It can. Content rendered only by JavaScript after page load may be indexed late or incompletely. Server rendering or static generation avoids the problem. For content pages the simplest solution is to not depend on JavaScript for the content itself.
A quick check: view the page source and search for your main heading. If it is not there, the content depends on JavaScript execution.
What is crawl budget and does it matter?
It is how much crawling effort a search engine spends on your site. For small sites it rarely matters. For large sites — particularly stores generating many filter and parameter URLs — crawling effort spent on near-duplicates is effort not spent on pages that could rank.
The practical fix is controlling which parameter and filter combinations are crawlable, rather than trying to increase crawl budget directly.
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