SSL is short for Secure Sockets Layer and is a protocol that was developed by Netscape to transmit private documents securely via the Internet.
SSL works by using a private key to encrypt data that is transferred over the SSL connection.
The SSL protocol uses digital certificates (i.e. SSL certificates) to create a secure, confidential communications 'pipe' between two entities.
Data transmitted over an SSL connection cannot be tampered with or forged without the two parties becoming immediately aware of it.