Digital Video Recorders (DVR's) come in 4, 9 or 16 Channel configurations. In addition to DVD-RW Drive, you can choose a 500GB or 1TB Hard Drive configuration for your dvr. This means the length of time a DVR can record will exceed 30 days. One can also connect a DVR to the internet. This will enable an authorized person with the correct password to view and control the video from anywhere in the world.