When you browse the internet, your browser constantly communicates with web servers using HTTP (Hypertext Transfer Protocol). Every request you make — whether it’s clicking a link, submitting a form, or loading a page — gets a response from the server.

That response includes something called an HTTP Status Code. These are three-digit numbers that tell you (and your browser) what happened with your request.

Sometimes you see them directly (like 404 Not Found), but most work silently in the background. Understanding them helps developers, website owners, and even curious users make sense of what’s going on.

Categories of HTTP Status Codes

HTTP status codes are grouped into five categories, based on their first digit:

1xx – Informational
- The request is received, and the server is still processing it.
- Rarely seen by end-users.
2xx – Success
- The request was successfully processed.
3xx – Redirection
- The client needs to take further action (like being redirected to another URL).
4xx – Client Errors
- Something went wrong with the request (e.g., page doesn’t exist).
5xx – Server Errors
- The server failed to process a valid request.

Common HTTP Status Codes You Should Know

✅ 200 OK

Means: Everything worked fine.
Example: Visiting a webpage that loads successfully.

✅ 301 Moved Permanently

Means: The requested page has been permanently moved to a new URL.
Example: A website changes domain, and old links redirect to the new one.
Important for SEO because it transfers link equity to the new page.

✅ 302 Found (Temporary Redirect)

Means: The page temporarily resides at another URL.
Example: Used when testing a new page but keeping the old one live.

❌ 400 Bad Request

Means: The server couldn’t understand the request (malformed syntax).
Example: A browser sends corrupted or invalid data.

❌ 401 Unauthorized

Means: Authentication is required but not provided or incorrect.
Example: Trying to access a private dashboard without logging in.

❌ 403 Forbidden

Means: The server understands the request but refuses to authorize it.
Example: Trying to access admin pages without permission.

❌ 404 Not Found

Means: The server couldn’t find the requested page.
Example: Clicking a broken link or mistyping a URL.
One of the most common errors users see.

⚠️ 500 Internal Server Error

Means: The server encountered an unexpected error.
Example: Server misconfigurations, script errors, or database crashes.

⚠️ 502 Bad Gateway

Means: One server acting as a gateway received an invalid response from another server.
Example: CDN (like Cloudflare) can’t communicate with the origin server.

⚠️ 503 Service Unavailable

Means: The server is temporarily unavailable (overloaded or down for maintenance).
Example: High traffic spike during a sale causes downtime.

⚠️ 504 Gateway Timeout

Means: The server acting as a gateway didn’t receive a timely response.
Example: When a request to a third-party API takes too long.

Why HTTP Status Codes Matter?

For Developers – Helps debug issues quickly (client vs server problems).
For SEO – Google bots rely on status codes to index pages correctly.
For Users – Gives clues on why a website isn’t working.

Real-World Analogy

Think of HTTP status codes like a restaurant experience:

200 OK – Your order arrives perfectly.
301 Redirect – “We’ve moved to a new location, here’s the address.”
404 Not Found – “Sorry, we don’t have that dish on the menu.”
500 Internal Error – “The kitchen caught fire, we can’t serve you right now.”

Conclusion

HTTP status codes may look like mysterious numbers, but they’re essential in understanding how the web works. Whether you’re a developer fixing issues, an SEO professional tracking redirects, or just a curious user, knowing these codes helps you navigate the internet with confidence.

Common HTTP Status Code : What Do They Mean?