The original Xbox had a built-in hard drive with an 8 GB capacity.
This internal drive was a major design feature because it let the console save games without requiring a separate memory card. It also stored downloaded content and supported the Xbox operating system. The drive was an ordinary hard-disk component rather than the removable cartridge-based storage used by some earlier consoles.
The capacity is sometimes misremembered as 10 GB because later Xbox models and replacement drives used different sizes. The original Xbox also included a DVD-ROM drive, but games were distributed on optical discs and did not require the hard drive for basic installation.