A Certificate Signing Request (CSR) is needed if you want to obtain an SSL certificate that will encode all the payment and login information which are exchanged between your website and its customers. The CSR contains information about the website plus its owner in Base64-encoded form - web address, physical address and email, company name and unit, etc. Based upon this code, a licensed SSL vendor provides you with the certificate, that is digitally signed with the vendor's private key in order to identify that they're a dependable issuer. At the time of 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 plus the CSR. Then, you will be able to use a URL that starts with https:// for your site rather than http:// and the website visitors can view the info that you've provided for the CSR using their Internet browsers.