Computers haven't been around all that long, but they've already left a legacy - and for most companies it's a nightmare. As companies move to more modern and sophisticated computer systems, they have to find a way to integrate their old or "legacy" systems into the new system. That's not always easy. The old systems often were written specifically for the functions they performed. Data can't always be transferred. In some cases, the old systems have to be kept running and the new systems are rigged to pull data from the older system as necessary.