TLS (Transport Layer Security) formerly known as Secure Socket Layer (SSL) is a Protocol used by applications to communicate securely across a network, preventing tampering with eavesdropping on email, web browsing, messaging, and other protocols.
Both TLS and SSL are client/server protocols that ensure communication privacy by using cryptographic protocols to provide security over a network.
When a server and client communicate using TLS, it ensures that no third party can eavesdrop or tamper with any message.