OpenSSL is an open-source cryptographic library that provides secure communication over computer networks. It implements the SSL (Secure Sockets Layer) and TLS (Transport Layer Security) protocols, ensuring encryption, authentication, and data integrity for applications like web servers, email clients, and VPNs.

**Key Features of OpenSSL:**

**Cryptographic Functions**: Supports encryption, decryption, hashing, and digital signatures.

**Certificate Management**: Generates and manages X.509 certificates for secure authentication.

**Command-Line Utility**: Offers various commands for cryptographic operations.

**Cross-Platform Compatibility**: Available for Linux, Windows, macOS, and BSD systems.

OpenSSL is widely used in securing internet communications, including HTTPS websites and secure email transmissions.