The computer chip, often known simply as a chip, in lowercase to distinguish it from the main character, is a tile in Chip's Challenge, which typically Chip must collect a specified number of in order to open the socket to reach the exit.
Some levels have no chips required, which allows Chip to immediately open any existing sockets (only Castle Moat has no chips and has sockets in CC1), and some levels have extra chips placed in the level, though some extra chips may be inaccessible (see Lesson 6) or skippable entirely due to a mistake in the programming or a glitch of some type. Examples of these, known as one type of busted level, are Tossed Salad, Three Doors, Hidden Danger, and Scoundrel.
Chip is free to collect extra chips beyond the number required to clear the level, though in most cases this will only serve to delay him. All sockets in the level can be freely opened (and will be left open) once Chip has collected the level's specified number of chips; he does not have to collect any of them over again to pass through multiple sockets or one socket multiple times.