Unetbootin stands for 'Universal Netboot Installer'; it is a program used to install disk images or isos onto USB drives. Questions about using unetbootin in Ubuntu or with Ubuntu images should use this tag.
Unetbootin
can use iso that you produce or it can download the necessary files and create LiveCD systems. In general it supports a huge number of Linux distributions and it can run on both Windows and Linux based operating systems.
The program is installed from the repositories and the official site is here there you can find further information on the program's capabilities.