Kali Linux is a Debian-derived Linux distribution designed for penetration testing and digital forensics. It is maintained by Offensive Security and contains over 300 security and forensics tools. Kali Linux originated from previous penetration testing distributions like BackTrack, which it replaced in 2013. Some key features of Kali Linux include being preinstalled with tools like nmap, Wireshark, and John the Ripper, as well as supporting live booting, virtual machines, and ARM devices like Raspberry Pi.