404s

A 404 error, short for HTTP 404 Not Found, is a standard response code indicating that the client could not locate the requested resource on the server. It is part of the HTTP protocol and signals that the server is reachable but does not have the content at the specified URL.

404s commonly arise from broken or outdated links, mistyped URLs, recently moved or renamed pages without a corresponding redirect, or links to resources that never existed. Other factors include URL parameter changes, case sensitivity on the server, and issues introduced during site maintenance.

When a non-existent page is requested, the server returns a 404 status. Browsers typically display a default or customized 404 page. Some servers may emit a "soft 404"—a 200 OK status with a page that says not found—which can mislead users and search engines.

Impact and handling: from an SEO perspective, 404s are normal but excessive or poorly managed 404s can degrade user experience and crawl efficiency. Use 301 redirects for permanently moved content and 302/307 redirects for temporary changes, or a 503 status if the site is temporarily unavailable. Maintain a well-designed 404 page that helps users find what they wanted, such as site navigation or a search box, and log 404s to fix broken links.

Best practices include regularly auditing site links, implementing appropriate redirects, correcting typos, keeping sitemaps in sync with available content, and distinguishing between 404 and 410 Gone for permanently removed resources. This helps preserve user experience and search engine health.