Kali contains a vast array of hacker tools and utilities (password attacks, sniffing and spoofing, reverse engineering, ...). Hacking foreign WiFi/WLAN (wireless attacks) and more. Kali is designed for digital forensics and penetration testing.

Kali is preinstalled with numerous penetration-testing programs, including nmap (a port scanner), Wireshark (a packet analyzer), John the Ripper (a password cracker), and Aircrack-ng (a software suite for penetration-testing wireless LANs). Kali can be run from a hard disk, live DVD, or live USB.
The most advanced penetrating testing distribution, ever.
Kali, the most advanced and versatile penetration testing distribution ever created. Kali has grown far beyond its humble roots as a live DVD and has now become a full-fledged operating system.
Note: Kali is Linux based, but suitable for all Windows versions.