SSL - Secure Sockets Layer:

SSL or Secure Sockets Layer is a protocol that transmits private documents through the Internet. It creates a secure connection between a client and a server over which any amount of data can be sent securely.

SSL works by using a private key to encrypt data transferred over the SSL connection.

By convention, URLs that require an SSL connection start with https: instead of http:

Hosting.ph clients must purchase an SSL certificate before the Web site can be secured.