Though the Apple Watch is designed to be used with an iPhone, there are times you may want to take it out on its own--say, if you're exercising. Fortunately, onboard storage means you won't have to forego your workout tunes: The Watch has 8GB of flash storage onboard, 2GB of which is reserved for music. (The rest is used for the Watch's operating system and apps, with 75MB reserved for tiny photos.) If that seems paltry, keep in mind that Apple's iPod shuffle has 2GB of storage, which Apple says can store "hundreds" of songs. So probably plenty for your three-mile run.