HTTP status codes are sent by web servers whenever a human internet browser or a search engine spider tries to view your website. Most of the time, a human user logging onto your
website wouldn’t see a HTTP status code so long as everything is okay, although there are some common codes that many internet users will likely be familiar with.
We’ll mention these as we go through this post, but for a good understanding it is better to go through what each type of status code is, and when it will typically be utilized.
Provisional Responses: 100’s
There are only two provisional responses, both of which require the user or the search spider to take action to continue. The two responses are 100, which is continue, and 101, which informs the user of a switch in protocols.
When a server sends this status code they are saying that a request has been successful. The most common success status code is 200, which means you’ve got the page and information you requested 100% successfully, although there are other status codes that mean a request has been successful but not fully met. For example, a request might be successful but not return any content, or the request might be successful after information has been sourced from another location.
A 3xx code means that the server needs to take further action to fulfill the request. Most 3xx codes involving redirection to another page or website. Using redirects and 3xx requests correctly is important if you are redesigning your website
and have new URL structures and sections. If you don’t use them, users would find blank pages and receive the types of error we’re going to look at next.
Request Error: 400’s
This is the type of error that a human internet user will most commonly see. The two errors likely to be encountered are the 403 error, which means you are not authorized to view a page, and a 404 error, which means the server couldn’t find the page. 404 errors can occur for a number of reasons, typically because a 301 redirect request hasn’t been used or because of a typography error in the request. Some websites will identify their most commonly landed on 404 pages and set up 301 redirects as a result.
Server Errors: 500’s
Server errors are exactly what they say they are, meaning there was no problem with the request itself. Server errors can happen for a number of reasons, and from a hosting providers
perspective they are something you should be looking to eradicate as much as possible, or else you could quickly find yourself losing traffic and customers.