DVD (which stands for Dynamic Video Device) is a device used to hold and play movies. It was invented in the late twenty first century, replacing the more primitive VHS. The DVD is much more powerful and awesome, and it is all we use now. It will be in use until the Blu-Ray is invented in a few hundred years.
To create a DVD, a company must first take a sheet of an unknown material, and cut it into a circular shape with a hole. It is shaped like this because the inventor of DVDs really likes donuts. Then, they burn information onto the disk (using a laser). When placed in a DVD player, a second laser extracts the information, and displays it on your screen.
The DVD was difficult to invent, as the inventor often had the laser fry his disks, or simply couldn't get the laser on. The worst was when the laser machine went mad, and started shooting at Everybody screaming "KILL KILL KILL!" This was eventually fixed.
DVD is superior to the VHS used by Ancient Geeks, but inferior to the Blu-Ray used in the future, when they have flying cars. If you disagree, then C2 will come in and roundhouse kick your head off (the real Chuck Norris doesn't care enough). So, just use the DVD. If you get your hands on a Blu-Ray, then they are illegal because it means someone was breaking international time-travel laws.
DVDs are currently sold at any location that sells DVDs.
Everybody knows that a DVD is just a glorified bagel