Complex sentence: Digital cable is a term for a type of cable television that delivers more channels than normally possible; this is accomplished by using video compression and a digital signal (as opposed to analog) and almost always requires the customer to use a set-top box.
Split into simpler sentences: Digital cable is a term for a type of cable television that delivers more channels than normally possible by using video compression and a digital signal (as opposed to analog). This almost always requires the customer to use a set-top box.