Viscosity software (version 1.5.4) is a VPN client that enables users to connect to a variety of VPN protocols, including OpenVPN, PPTP, and L2TP/IPsec. The software offers advanced features such as DNS leak protection, IPv6 leak protection, and traffic obfuscation to enhance privacy and security. Users can easily switch between VPN servers and customize connection settings, and the software also supports split-tunneling and automatic connection on startup.