What is 404 Error?
The standard "not found" response for dead URLs. Expected in small numbers after content removal; a spike means broken internal links or a bad migration map.
Related terms
410 Gone
An explicit "permanently removed" status, stronger than 404. Use it for deliberately retired pages with no equivalent, so engines drop them faster instead of rechecking.
Soft 404
A page that looks like an error (empty listing, "no results") but returns HTTP 200. Engines treat it as low quality; audits should return real 404/410 statuses for dead ends.
Broken Link Building
Finding dead outbound links on relevant pages and offering your live resource as a replacement. High success rate because you solve the webmaster’s problem first.
Technical SEO
The crawling, indexing, rendering, and performance work that lets search engines reach, understand, and serve your pages. It covers directives, architecture, speed, and structured data rather than words on the page.
Crawling
How search-engine bots discover pages by following links, sitemaps, and directives. If a URL is never crawled, it cannot be indexed no matter how good its content is.
Crawl Budget
The number of pages a search engine will crawl on a site in a given period, driven by server capacity and demand signals. Large or slow sites must spend it on indexable, valuable URLs.