public SSL/TLS is used to provide a secure connection between a client and a server.
Key elements
Authentication
The server sends a certificate to the client. The client can use this to authenticate the server at a well-known certificate authority (CA). See Authentication and authorization
Encryption
private-/public-keys are used to encrypt any communication between the client and the server
Integrity
Every transmission is provided with a hash, that only maps to the transmission, if it wasn’t manipulated. Using HMAC it is ensured, that the hash isn’t manipulated.