Transport Layer Security (TLS) is a cryptographic protocol designed to provide end-to-end security of data sent between applications over the Internet. It is widely used in applications such as email, instant messaging, and voice over IP, but its use in securing web browsing sessions is most familiar to users. TLS is a proposed Internet Engineering Task Force (IETF) standard, first defined in 1999, and the current version is TLS 1.3, defined in August 2018. TLS builds on the now-deprecated SSL (Secure Sockets Layer) specifications developed by Netscape Communications for adding the HTTPS protocol to their Navigator web browser.

TLS is normally implemented on top of TCP in order to encrypt Application Layer protocols such as HTTP, FTP, SMTP, and IMAP, although it can also be implemented on UDP, DCCP, and SCTP as well (e.g. for VPN and SIP-based application uses). This is known as Datagram Transport Layer Security (DTLS) . DTLS is a related communications protocol that provides security to datagram-based applications by allowing them to communicate in a way designed to prevent eavesdropping, tampering, or message forgery.

TLS uses encryption for the client and server to generate a secure connection between the applications. It begins when users access a secured website by specifying the TLS encryption method like the advanced encryption standard (AES) . TLS provides several benefits, including encryption, interoperability, algorithm flexibility, ease of deployment, and ease of use.