Many newer computers (particularly desktop computers) will come with a built-in TV tuner card.

If you are not sure whether your computer has a TV tuner card, take a look at the documentation and disks you received when you purchased your computer.

If your computer has a built-in TV tuner card, it will be listed as a feature of your computer and there should be a disk from the TV tuner card manufacturer with the driver and installation software for your tuner.