What is a live DVD?
A live CD/DVD or live disk contains a bootable operating system, the core program of any computer, which is designed to run all your programs and manage all your hardware and software.
Live CDs/DVDs have the ability to run a complete, modern OS on a computer even without secondary storage, such as a hard disk drive. The CD/DVD directly runs the OS and other applications from the DVD drive itself. Thus, a live disk allows you to try the OS before you install it, without erasing or installing anything on your current system. Such disks are used to demonstrate features or try out a release. They are also used to test hardware functionality, before actual installation. To run a live DVD, you need to boot your computer using the disk in the ROM drive. To know how to set a boot device in BIOS, please refer to the hardware documentation for your computer/laptop.