Kali Linux is a Debian-derived Linux distribution designed for digital forensics and penetration testing. It contains over 300 security tools and can run on various hardware architectures. Kali is an updated version of BackTrack, which it replaced in 2013 to address dependency issues. Some key tools included are nmap, Wireshark, John the Ripper, and Aircrack-ng. It is maintained by Offensive Security and intended to perform tests from an attacker's perspective to evaluate system vulnerabilities.