Transport Layer Security is the standard protocol that encrypts network traffic between two endpoints, such as a browser and a server. It also uses digital certificates to prove identity, so a client can verify it is talking to the intended service and not an impostor. TLS is the foundation of HTTPS, secure APIs, email transport, and many enterprise service-to-service connections.
In cybersecurity, TLS matters because it protects confidentiality and integrity in transit, reducing eavesdropping and tampering. Attackers often target the trust layer around TLS rather than the encryption itself, using rogue certificates, misconfigured certificate validation, or compromised certificate authorities to intercept traffic. Defenders rely on TLS configuration, certificate lifecycle management, and trust-store hygiene to keep encrypted sessions both private and authenticated. In post-quantum migration, TLS becomes especially important because new signature schemes must still fit the certificate and validation workflows that TLS depends on.