An HTTP status code is a three-digit message a website’s server sends to a browser in response to a request. While you don’t always see them, search engines like Google use these codes to understand the status of your web pages. Correctly managing these codes is essential for technical SEO, as it directly impacts how your site is crawled, indexed, and ranked.
The Five HTTP Status Code Classes
HTTP status codes are grouped into five classes, with the first digit of the code defining its category.
- 1xx (Informational): The server has received the request and is continuing the process.
- 2xx (Successful): The request was successfully received, understood, and accepted. A 200 OK status code is the ideal signal to Google that a page is healthy and ready for indexing.
- 3xx (Redirection): The request needs to be completed with further action, usually a redirect to another location. These codes are critical for managing site migrations and URL changes.
- 4xx (Client Error): The request contains bad syntax or the page cannot be fulfilled due to a client-side issue. This includes common errors like 404 Not Found. Google will ignore any content from a URL that returns a 4xx error and will remove the URL from its index.
- 5xx (Server Error): The server failed to fulfill a seemingly valid request. This indicates a server-side problem. Pages with a 5xx status code will not be indexed and can cause Google’s crawlers to slow down, negatively impacting your site’s overall health and rankings.
Key Status Codes for SEO
While there are many HTTP status codes, a few are particularly important for maintaining your website’s health and SEO performance.
- 200 OK: This is the green light. It confirms that a page is live and accessible, allowing search engine bots to crawl and potentially index the content.
- 301 Moved Permanently: This is the best code to use for a permanent URL change. A 301 redirect passes a significant portion of the original URL’s “link equity” (authority) to the new page, preserving its SEO value. It tells search engines to update their records permanently.
- 302 Found: Used for temporary redirects. It signals that the page has moved temporarily and the original URL may be used again. Google may not pass link equity for a 302, so it shouldn’t be used for permanent changes.
- 404 Not Found: This means the requested page doesn’t exist. While a few 404s are normal, an excessive number can signal to Google that your site is poorly maintained. It’s a best practice to create a custom 404 page to help users find their way back to your site.
- 410 Gone: This code tells search engines that a page has been permanently removed and is not coming back. Google treats a 410 with more finality than a 404, which can lead to faster de-indexing. It is ideal for content you have intentionally deleted.
- 503 Service Unavailable: This indicates the server is temporarily unable to handle the request, often due to maintenance or overload. Using a 503 during planned downtime is a good practice, as it tells search engines to check back later without dropping your page from the index.
Ignoring server errors (5xx) or a large number of broken links (4xx) sends a negative signal to search engines. Consistent errors can hurt your crawl budget and authority, suggesting to Google that your website is not a high-quality resource. Regularly monitoring your site’s health through tools like Google Search Console is essential for identifying and fixing these issues quickly.
