A Certificate Signing Request (CSR) is required when you wish to acquire an SSL certificate that will encode all the payment and login information which will be exchanged between your website and its visitors. The CSR contains info about the website plus its owner in Base64-encoded form - website address, physical address along with e-mail, company name and unit, etc. Based upon this code, an authorized SSL vendor provides you with the certificate, that's digitally signed with the vendor's private key to identify that they are a dependable issuer. During the CSR generation, a unique private key is also generated and the set up of the SSL involves all of the 4 codes - the two keys, the certificate plus the CSR. After that, you will be able to use a URL that starts with https:// for your website rather than http:// and the website visitors can view the information that you have provided for the CSR using their web browsers.