Every time you visit a website, the server returns a 3-digit code. Most of the time, you don't see it (because it's a 200 OK). But when things go wrong, understanding these codes is the key to fixing them.

2xx: Success

200 OK: The standard response for successful HTTP requests. Everything is working.

3xx: Redirection

301 Moved Permanently: The page has moved to a new URL forever. SEO value is passed to the new URL.

302 Found: The page is temporarily at a new URL. SEO value stays with the old URL.

4xx: Client Errors (It's You)

400 Bad Request: The server couldn't understand your request (often malformed syntax).

401 Unauthorized: You need to log in.

403 Forbidden: You are logged in, but you don't have permission to view this.

404 Not Found: The classic. The page doesn't exist.

5xx: Server Errors (It's Them)

500 Internal Server Error: A generic error message. Something crashed on the server.

502 Bad Gateway: One server received an invalid response from another (common with reverse proxies like Nginx).

503 Service Unavailable: The server is overloaded or down for maintenance.

Why Monitor These?

A spike in 5xx errors means your server is crashing. A spike in 404s might mean a broken link. Monitoring these codes with a tool like Pingbird gives you immediate insight into your site's health.