Kali Linux is a Debian-derived Linux distribution designed for digital forensics and penetration testing. It contains over 600 security tools for tasks like reconnaissance, vulnerability assessment, password attacks, and wireless attacks. It is pre-installed with tools like Nmap, Wireshark, Aircrack-ng, Hydra, and Burpsuite. Kali Linux can also be installed on Android devices through tools like Linux Deploy to enable penetration testing on mobile networks and devices.