Just like a computer or high-capacity standalone music player, a phone can include a hard disk drive (HDD). Typically, a built-in hard drive can store anywhere from 10 - 100 times as much information as built-in memory chips in a phone.

This allows the phone to store whole music collections, instead of just a few songs, or large amounts of high-quality photos and/or video.

The trade-off of a hard drive is usually added size and weight.