External drives are available in both DVD and Blue-Ray format. These drives connect via USB in the same way an external hard drive would. They provide the same functionality as internal drives and can be plugged in and out while the computer is on. And they could be carried out easily.

For old motherboards, there may have trouble installing older operating systems such as windows XP from one these drives. Now for new computers with new motherboard, we could use the external driver to instal the system. The external dvd drive is portable and potential in storage.