Ubuntu is an ancient African word meaning ‘humanity to others’. It is often described as reminding us that ‘I am what I am because of who we all are’. We bring the spirit of Ubuntu to the world of computers and software. The Ubuntu distribution represents the best of what the world’s software community has shared with the world.
Kali Linux is a Debian-derived Linux distribution designed for digital forensics and penetration testing. It is maintained and funded by Offensive Security Ltd. It was developed by Mati Aharoni and Devon Kearns of Offensive Security through the rewrite of BackTrack, their previous information security testing Linux distribution based on Knoppix. The third core developer Raphaël Hertzog joined them as a Debian expert
CentOS is designed to be super-reliable, which is why it’s a great choice for a server. It's not quite such a good bet for someone looking for a new OS for daily use on their desktop PC or laptop.