TLS

TLS (Transport Layer Security) is a cryptographic protocol that secures communication between devices on a network. It delivers three pillars of security: confidentiality (data is encrypted and unreadable to third parties), integrity (a guarantee that the message was not altered in transit) and authentication (confirmation of the server's identity through a certificate). TLS is the direct successor to the deprecated SSL protocol, and it is what powers the secure version of the HTTPS protocol.

How TLS works

A secured connection begins with a so-called handshake — a negotiation between client and server. During it the parties agree on the supported protocol version and a set of algorithms (the cipher suite), the server presents its certificate, and the client verifies it. Using asymmetric cryptography, the parties derive a shared session key, which then encrypts the actual traffic with far faster symmetric cryptography. The latest version, TLS 1.3, simplified this process and shortened the handshake to a single round trip, so connections establish faster and more securely than in TLS 1.2. The older 1.0 and 1.1 versions were found vulnerable and withdrawn from use.

Practical application

TLS protects almost every sensitive transmission on the internet: bank logins, store payments, form submissions, email (SMTP, IMAP), and also database and API connections. Without it, data would travel in plaintext, exposed to interception in a man-in-the-middle attack. For a site owner, deploying TLS means installing a valid certificate and forcing an encrypted connection — ideally reinforced with the HSTS header, which tells the browser to always connect over HTTPS. Properly configured TLS is now a standard that both users and search engines expect.