What is a CSR?

When you secure your site with SSL you are creating a trusted connection with your site's users. In order to create this connection, both sides need to verify that they are exactly who they say they are.

This is to prevent certain types of cyber attacks. For example, a so-called "Man-in-the-middle" attack can create a copy of a trusted site that looks exactly like it. When people enter their login details into the site, it simply returns an error. In the meantime, the attackers have already logged into the accounts (using the details submitted through the fake malicious site) and stolen all their information!

This obviously isn't good, so the way a site equipped with an SSL Certificate can stop this from happening is by verifying its identity. Even if an attacker can visually recreate portions of a site, they can never use the same domain name and identifying information as the original site. The more information, the better. That is why certificates with more validation are more trusted.

So, in order to create an SSL Certificate, you need to submit some pieces of information. Here is some of the information that a CSR normally needs, although in the case of EV SSL Certificates, this may be considerably greater:

All of this information is encrypted in the CSR and used when you create your SSL Certificate to ensure that nobody is ever able to compromise the security of your connections with your users.