OpenSSL is an open-source cryptographic library that software uses to implement TLS, SSL, certificate handling, encryption, and related security functions. It is not usually a user-facing product; instead, it is a shared security component embedded in web servers, APIs, mail systems, VPN tools, appliances, and other software that needs secure transport.
In cyber security, OpenSSL matters because a flaw in the library can affect many products at once. Attackers may look for vulnerable versions, weak protocol settings, or features that expose a reachable code path. Defenders use it for trusted encryption, certificate validation, and secure communication, but they must also track which applications depend on which OpenSSL branch and whether fixes have been backported. Patching OpenSSL is often only part of the job: teams also need inventory, configuration review, and service testing to make sure the update actually removes risk.