HTTP codes also known as “HTTP status codes,” are standard response codes given by web server software for every request made to the server. These codes are part of the HTTP (Hypertext Transfer Protocol) response header and indicate whether a specific HTTP request has been successfully completed. Understanding HTTP codes is crucial for SEO (Search Engine Optimization) professionals, web developers, and system administrators as they help identify and troubleshoot website issues that could affect a site’s usability, performance, and visibility in search engine results.

HTTP codes are divided into five categories, each indicated by the first digit of the code:

1. 1xx (Informational): These codes indicate a provisional response and that the request by the client is being processed. For example, 100 Continue means that the server has received the request headers, and the client should proceed to send the request body.
2. 2xx (Success): This category signals that the client’s request was successfully received, understood, and accepted. For instance, 200 OK is the standard response for successful HTTP requests, and 201 Created indicates that the request has led to the creation of a new resource.
3. 3xx (Redirection): These codes tell the client that further action needs to be taken in order to complete the request. This often involves being redirected to another URL. 301 Moved Permanently and 302 Found are common redirection codes that are particularly important for SEO, as they indicate the permanent or temporary relocation of a URL, respectively.
4. 4xx (Client Error): This group of status codes indicates that the request contains bad syntax or cannot be fulfilled. 404 Not Found is a well-known code indicating that the server can’t find the requested resource, crucial for SEO to identify broken links on a site. 403 Forbidden and 401 Unauthorized are other examples indicating permission-related errors.
5. 5xx (Server Error): These indicate that the server failed to fulfill an apparently valid request, pointing to errors on the server side. 500 Internal Server Error suggests a generic error when an unexpected condition was encountered, and 503 Service Unavailable indicates that the server is not ready to handle the request, often due to maintenance or overload.

For SEO, paying close attention to 3xx, 4xx, and 5xx codes is essential. Properly managing redirects (3xx) ensures that link equity is passed to the correct URLs, while identifying and fixing broken links (4xx) can improve user experience and crawl efficiency. Addressing server errors (5xx) quickly is crucial to ensure that a site remains accessible and reliable. Monitoring and optimizing for these HTTP status codes can significantly impact a website’s search engine rankings and user satisfaction.