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HTTP Status Codes Glossary

This list is an easy-to-reference database of HTTP status codes with their definitions and helpful code references all in one place. Visit an individual status code via https://www.webfx.com/web-development/glossary/http-status-codes/what-is-a-___-status-code/ or browse the list below.

1xx Informational

2×× Success

3×× Redirection

4×× Client Error

5×× Server Error

Additional resources

FAQs about HTTP status codes

Learn more about HTTP status codes with these FAQs:

What are HTTP status codes?

HTTP status codes are three-digit numbers that are returned by servers to indicate the status of a client’s request. When a client (such as a web browser) makes a request to a server, the server will respond with a status code and a message indicating whether the request was successful or not.

What are the HTTP status code classes?

There are five classes of HTTP status codes, each identified by the first digit of the three-digit status code. The classes are as follows:

1xx (Informational)

These status codes indicate that the server has received the request and is continuing to process it. They are primarily used to convey information about the status of the request while it is being processed.

2xx (Successful)

These status codes indicate that the request was successfully received, understood, and accepted by the server. They are typically used to indicate that the requested action has been successfully completed.

3xx (Redirection)

These status codes indicate that the client needs to take additional action to complete the request. They are typically used to redirect the client to a different resource or location.

4xx (Client Error)

These status codes indicate that the server cannot process the request because the client has made an error. They are typically caused by issues such as invalid input, authentication problems, or insufficient permissions.

5xx (Server Error)

These status codes indicate that the server encountered an error while processing the request. They are typically caused by issues such as server overload, programming errors, or infrastructure problems.

Which HTTP status codes affect SEO?

Several HTTP status codes are important for SEO, including:

200 OK

This is the most common status code and indicates that the server has successfully processed the request and returned the requested resource. This is the ideal status code to receive for search engine optimization purposes as it indicates that the content is available and accessible to both users and search engines.

301 Moved Permanently

This status code indicates that the requested resource has been permanently moved to a new URL. This is important for SEO because it ensures that search engines can redirect users to the new URL and transfer the SEO value of the old URL to the new one.

404 Not Found

This status code indicates that the requested resource is not available on the server. This can be problematic for SEO because it indicates to both users and search engines that the content is not available. It is important to fix 404 errors as soon as possible to avoid losing SEO value and providing a poor user experience.

503 Service Unavailable

This status code indicates that the server is temporarily unavailable due to maintenance or overload. This can be problematic for SEO because search engines may interpret this as a sign of an unreliable website. It is important to fix 503 errors as soon as possible to avoid losing SEO value and providing a poor user experience.

In general, it is important to monitor and fix any HTTP status codes that could negatively impact user experience or search engine indexing.

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