U.S. copyright law
"Digital transmission means that the original source is converted into and transmitted as a series of digits in binary code (i.e. 0s or 1s). The string of binary digits can be compressed (Data compression) and then re-expanded on arrival, thus economising on transmission capacity. For example, whereas cable TV networks can usually only deliver some 30 to 40 channels using analogue transmission technology, digital cable networks can offer not only hundreds of TV channels but also interactive services, voice telephony and fast Internet access. There is a trade-off to be made between the number of channels and the quality level desired."