What role does Security Sockets Layer (SSL) play in data communication?

Security Sockets Layer (SSL) primarily functions to secure data in transit between a client and a server by providing encryption, ensuring that the data cannot be intercepted or tampered with during transmission. This is vital for protecting sensitive information, such as login credentials or financial data, when communicated over the internet.

One of the key roles of SSL is to facilitate authentication between the server and client. This ensures that the client is communicating with the intended server and not an imposter, which is crucial for establishing trust. SSL achieves this through a process known as the SSL handshake, where certificates are exchanged and verified, confirming authenticity.

While some other options reference significant concepts, they do not directly align with the primary role of SSL. Encryption of data at rest is handled by different security protocols and methods outside the scope of SSL, which addresses data in transit. While FTP is a protocol for transferring files, it does not inherently use SSL unless specifically configured to utilize it, such as in FTPS (FTP Secure). Lastly, SSL does not function as a firewall; firewalls are network security devices that monitor and control incoming and outgoing network traffic based on predetermined security rules, serving a different purpose in overall cybersecurity.