OpenSSL is a popular open-source software library that provides tools for implementing SSL (Secure Sockets Layer) and TLS (Transport Layer Security) protocols. These protocols are essential for encrypting data transmitted over the internet, ensuring secure communication between web browsers, servers, and other devices. OpenSSL is widely used by websites, applications, and network services to protect sensitive information such as passwords, credit card numbers, and personal data from eavesdropping or tampering.