The iPhone and iPad are arguably Apple's most important product lines in this day and age but at the core, these devices are simply descendants of another key product that launched 12 years ago: the iPod.
Digital music was just starting to take hold in 2000 and at the time, there weren't a ton of options in general for listening to music. A traditional CD player cost around $75 and held about 15 songs per disc. Flash-based players did exist but they were also twice as expensive as a CD player and were limited to the same amount of storage.
An MP3 CD player and compatible disc could hold upwards of 150 songs which, priced at $150, brought the per song pricing to about a buck each. Hard drive-based music players capable of holding up to a 1,000 songs would set you back around $300 but were worth the investment as they brought per song pricing to just $0.30 each.
Steve Jobs wanted to jump into this market with a small device comparable to flash-based MP3 players that would fit inside your pocket and store the same 1,000 songs as larger hard drive-based solutions. The problem, however, is that such technology didn't exist as flash media at the time was limited to holding 10-20 tracks.
It wasn't until a chance meeting with Toshiba in early 2001 that Apple found a solution - a 1.8-inch hard drive with a capacity of 5GB. It was perfect for the iPod and soon after, Apple negotiated an exclusive deal with Toshiba for the technology.
Later that year, Jobs unveiled and subsequently launched the first iPod. It wasn't a smashing success at first but it ultimately proved wildly successful and brought Apple back from the brink of irrelevance.