A Certificate Signing Request (CSR) is required if you want to get an SSL certificate which will encrypt the payment and account details which are exchanged between your website and its users. The CSR contains info about the site as well as its owner in Base64-encoded form - web address, physical address and e-mail, company name and unit, and the like. Based upon this code, an accredited SSL vendor provides you with the certificate, that's digitally signed with the vendor's private key so as to show that they're a dependable issuer. During the CSR generation, a unique private key is also generated and the installation of the SSL involves all of the 4 codes - the two keys, the certificate as well as the CSR. Then, you'll be able to use a URL that begins with https:// for your website instead of http:// and the website visitors will be able to view the information that you've provided for the CSR using their Internet browsers.