OpenVPN, a VPN protocol and software, has been a popular tool for secure network connectivity since its first release in 2001. The protocol creates an encrypted tunnel between a client and a server, routing traffic through this tunnel to keep it private from anyone watching the connection. It uses the OpenSSL library and TLS to handle encryption and authentication, supporting strong algorithms like AES-256 and ChaCha20. It can operate over both UDP and TCP, with UDP being preferred for most use cases. OpenVPN can be self-hosted, giving organizations full control over their VPN infrastructure without relying on a third-party service. The open-source nature of the project means vulnerabilities are discovered quickly. The software is supported by a large and active community, with extensive documentation and configuration guides available online.