SSL certificate (Secure Sockets Layer certificate)

A Secure Sockets Layer certificate (SSL certificate) is a small data file installed on a Web server that allows for a secure connection between the server and a Web browser.

SSL certificates can be used by online enterprises wishing to encrypt credit card transactions, make data transfers, process logins and host secure social media websites. Based on the Secure Sockets Layer protocol developed by Netscape, SSL certificates use a cryptographic key to provide validation for a Web server, detailing its domain name, server name, hostname, company name and location. Most SSL certificates today also support the Transport Layer Security (TLS) protocol, which is considered to be more secure than SSL. 

SSL certificates are issued from a trusted certificate authority. There are three types of certificates: Extended Validation (EV) SSL certificates, Organization Validation (OV) SSL certificates and Domain Validation (DV) SSL certificates. When an SSL certificate is installed on a Web server, it activates the HTTPS protocol over port 443.  The use of an SSL certificate on a website is usually indicated by a padlock icon and a URL that begins with https://.