 A more modern example is a cassette tape (sequential — one must fast forward through earlier songs to get to later ones) and a CD (direct access — one can skip to the track wanted, knowing that it would be the one retrieved).In data structures, direct access implies the ability to access any entry in a list in constant time (independent of its position in the list and of the list's size).Very few data structures can make this guarantee other than arrays (and related structures like dynamic arrays).