HTTP Status Code

An HTTP status code is a three-digit number a web server returns to indicate the outcome of a browser's request. Every time a browser asks for a page, an image, or any other resource, the server answers with one of these codes, quietly reporting whether the request succeeded, was redirected, failed, or ran into a server problem. Most of the time visitors never see the number, because the browser simply shows the requested page, but the code is always there in the background, and it is essential information for anyone maintaining a site.

Status codes are grouped into ranges by their first digit, which signals the general category of response. Codes in the 200s mean success, with 200 being the standard "OK" that accompanies a normally delivered page. Codes in the 300s indicate redirection, telling the browser that the resource lives at a different address, either temporarily or permanently. Codes in the 400s mean the request failed for a reason on the client's side, the most familiar being 404, returned when a page cannot be found, or 403 when access is forbidden. Codes in the 500s mean the server itself encountered an error and could not fulfill an otherwise valid request. This tidy numbering lets both software and people quickly understand what happened without needing a lengthy explanation.

Status codes come from the Hypertext Transfer Protocol, the foundational language of the web, which was defined in the early 1990s and standardized as the web grew. The designers needed a compact, universal way for servers to communicate the result of every request, and a small set of numeric codes provided exactly that. The scheme has proven durable: the same basic categories have guided web communication for decades, with new specific codes added over time to handle situations the original set did not anticipate.

For a business, status codes matter because they directly affect how search engines and visitors experience a site. When search engines crawl a website, they read these codes to decide whether a page should be indexed, followed to a new location, or dropped from their records. A page that returns the right code when it moves preserves the ranking value built up over time, while a page that returns the wrong one can silently lose visibility. Server errors that persist can cause search engines to crawl a site less often and can frustrate customers who hit a broken page. Monitoring status codes is therefore a core part of keeping a site healthy and search-friendly.

Common mistakes include returning a success code for a page that is actually missing content, which creates so-called soft errors that confuse search engines, and using a temporary redirect when a move is actually permanent, which can prevent ranking value from transferring to the new address. Teams sometimes ignore recurring server errors, not realizing they are steadily damaging both user trust and search performance. Status codes relate closely to specific outcomes like the not-found error, the permanently removed response, and the temporary redirect, as well as to the secure protocol that carries all of these responses. Reading and managing status codes deliberately is one of the quiet disciplines that separates a well-run website from a neglected one.