PuTTY 0.77 is a free-to-use, open-source software that allows remote access to another computer. It supports several network protocols, including SCP, SSH, Telnet, and Rlogin. Additionally, the software features a comprehensive terminal emulator which is capable of emulating a wide range of protocols and it also comes with a command-line SCP and SFTP implementation. Furthermore, it provides a public key infrastructure for secure network communication and can be utilized for serial console operations.