The Disk

• Once a blank, writable DVD is placed in the tray and the tray is closed, the disk begins to quickly spin. The burner does this because the device's laser, which is used to access all data on the disk, aims only in one very specific place. With the disc spinning as fast as it does, it allows the drive to access all parts of the disk almost simultaneously.
  
  

Data Track

• A circle-shaped "track" of data is present on every writable layer (most DVDs have one layer, though when noted they may have two) of a DVD. Once data has been prepared by computer burning software and converted into fragments that the drive can understand, it is transmitted via the laser onto the disk itself until the track of data is full. When a disk is "finalized," that means it can no longer be changed and the data that is presently on it is the data that will be on it forever--unless you're using a rewritable DVD drive, which requires a special kind of disk and it itself has a special kind of laser for that specific purpose.
  
  

Speed

• DVD burners can author disks at various speeds. If your burner supports a top "speed" of 24x, that means that it can burn a disk 24 times faster than the "real time" of the content on the disk. That means if you are burning a movie that is 2 hours long, it will take you 24 times faster to burn the disk than to actually watch the movie. The same rule applies for data DVDs as well, only the speed in this case is measured against the time it would take to copy the file to a hard drive. So in that case a 24x burner would burn at 24 times faster than the amount of time it would take to copy the same amount of data using a hard drive.