A Certificate Signing Request (CSR) is required when you want to obtain an SSL certificate that will encode the payment and login info that are exchanged between your site and its clients. The CSR contains info about the website and its owner in Base64-encoded form - website address, physical address along with e-mail, company name and unit, etc. Based on this code, an accredited SSL vendor provides you with the certificate, that's digitally signed with the vendor's private key to show that they are a reliable 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 beginning with https:// for your site instead of http:// and your website visitors can view the information that you have provided for the CSR through their Internet browsers.