What Are HTTP Status Codes?
HTTP status codes are responses from the server to a client’s request. They tell you whether the request was successful or if something went wrong. Understanding these codes can help you quickly identify and resolve errors, optimize user experience, and improve your site’s SEO.
Success Codes: Indicating a Job Well Done
- 200: OK
The request succeeded.
This is the best-case scenario, indicating that the server successfully processed the request. - 201: Created
A new resource has been created.
Common in APIs when a new resource like a user or a post is created. - 202: Accepted
The request has been accepted but is still being processed.
Often used for asynchronous tasks, meaning the server will handle it, but it’s not done yet.
Redirection Codes: When Things Move Around
- 301: Moved Permanently
The resource has been permanently moved to a new URL.
Essential for maintaining SEO when redirecting old URLs to new ones. - 302: Found (Temporary Redirect)
The resource is temporarily located at a different URL.
Ideal for short-term redirects when content is temporarily moved. - 304: Not Modified
The cached version of the resource is used.
Improves page load speed by preventing the download of unchanged resources.
Client Error Codes: Identifying Issues on the Client Side
- 400: Bad Request
The request is invalid due to a syntax error or incorrect parameters.
Common when input data is wrong, or the request is malformed. - 401: Unauthorized
Authentication is required to access the resource.
This is a clear sign that users need to log in or provide valid credentials. - 403: Forbidden
The server refuses to perform the action.
Even with proper credentials, access is denied—often due to insufficient permissions. - 404: Not Found
The requested resource could not be found.
The most famous error on the internet, often caused by broken links. Use 301 redirects to prevent 404 errors. - 405: Method Not Allowed
The HTTP method used (GET, POST, etc.) is not supported by the resource.
This error occurs when a method isn’t allowed by the server for a particular URL. - 408: Request Timeout
The server took too long to respond.
Happens when a request is too slow or the connection is weak.
Server Error Codes: When the Issue Lies with the Server
- 500: Internal Server Error
A generic error indicating something went wrong on the server.
You’ll need to check server logs to figure out what went wrong. - 501: Not Implemented
The server doesn’t support the functionality needed to fulfill the request.
This can happen if a feature hasn’t been coded or is not yet functional. - 502: Bad Gateway
The server received an invalid response from an upstream server.
Often seen during server overloads or misconfigurations between web servers. - 504: Gateway Timeout
The upstream server took too long to respond.
Common when your server is waiting too long for a response from another server.
Why HTTP Status Codes Matter for SEO and Performance
Understanding and addressing HTTP status codes is essential for SEO. For example:
- 301 Redirects help preserve SEO value when URLs change.
- 404 Errors lead to broken links, harming user experience and search rankings.
- 500 Series Errors can lead to downtime, affecting both user trust and SEO performance.
By keeping track of your HTTP status codes, you can ensure a smoother experience for your visitors and avoid SEO penalties.
Final Thoughts
Whether you’re a developer or a site owner, knowing these 18 common HTTP status codes is vital to maintaining a well-functioning website. These codes give you insight into what’s happening behind the scenes and help you troubleshoot issues quickly.
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