What is TLS and how does it secure connections?

Answer

Transport Layer Security (TLS) is the protocol that encrypts data in transit, providing confidentiality, integrity, and server authentication for HTTPS and many other protocols. During the handshake the client and server agree on cipher suites and use the server's certificate, validated against a trusted certificate authority, to establish session keys via key exchange. Once established, application data is encrypted with symmetric keys for performance. TLS 1.3, the current major version, removed legacy insecure options and reduced the handshake to fewer round trips.