What is a Linux distribution?

Answer 1

A Linux Distribution (distro) is lika a flavour.

For example:

You can go to a dairy bar and ask for ice cream, but you need to specify which kind of ice cream. Chocolate ice cream, strawberry, bubble gum, etc...

You can run Linux, but you need to pick a specific type of Linux such as Ubuntu, OpenSuse, Fedora Core, Gentoo, Debian, Slackware, etc..

Different distros are generally suited for different things.

There are desktop distros like Ubuntu and Mint, that are focused on end users and doing your day to day stuff like browsing the internet, writing a report for work or school or MSNing your friends.

Some Linux distros are meant for running servers. These would be things like RedHat, Debian and Slackware. These will run your company website or an email server.

Answer 2

Ubuntu is by far the most common, next to its official and community variants Kubuntu, Lubuntu, and Xubuntu.

Ubuntu-based includes LuPu (Puppy Linux based off of Ubuntu), Linux Mint and Kali Linux (formerly Backtrack).

Debian and Debian-based distros include Ubuntu and Linux Mint Debian Edition.

Red Hat has RHEL (Red Hat Enterprise Linux), CentOS, and Fedora.

Also, Arch Linux with its derivatives Antergos, Black Arch, BBQLinux, and Manjaro.

Note that this is by no means a comprehensive list.