SSL Certificates provide secure, encrypted communications between a website and an internet browser. SSL stands for Secure Sockets Layer, the protocol which provides the encryption. SSL Certificates are typically installed on pages that require end-users to submit sensitive information over the internet like credit card details or passwords. Example pages include payment pages, online forms, and login pages.
SSL Certificates need to be issued from a trusted Certificate Authority. Browsers, operating systems, and mobile devices maintain list of trusted CA root certificates.