On Tuesday, Apple announced that it was discontinuing the iPod touch. In some ways, the announcement wasn't particularly surprising, aside from the fact that I'm pretty sure most people didn't even know Apple was still selling the iPod touch (I didn't). In that sense, killing off a product no one even remembered you were making is a bit anticlimactic. Now that we all use iPhones, there hasn't been a compelling reason to buy an iPod touch for years.

At the same time, the announcement is bittersweet, because it represents the end of a product that--more than almost any other--completely transformed the way we use technology. No, not the iPod touch. The iPod. 

Since it was introduced in October 2001, Apple has sold more than 400 million iPods. That makes it the company's second-most successful product ever, after the iPhone, which--having sold more than 1.5 billion devices--isn't just Apple's most successful product, it's the most successful product, ever.

You can draw a straight line between the success of the iPod and that of the iPhone. In fact, according to Tony Fadell, the man often referred to as "the father of the iPod," there would have been no iPhone without the iPod. 

Look, at the risk of making a dramatic understatement, Apple was a very different company 21 years ago than it is today. The month Apple released the iPod, it announced it lost $25 million the previous year, on a little less than $6 billion in sales. In its most recent quarter alone, the company made $25 billion in profit. The big difference is obviously the iPhone.

That wouldn't come for another six years, however. Steve Jobs, the company's iconic founder, had returned less than four years earlier and was in the middle of a dramatic effort to make Apple relevant. 

He had a hit with the iMac, the colorful all-in-one desktop computer that made computers fun and playful. By 2001, Apple had sold five million iMacs, but sales had started to slow. The iMac might have been the product that saved Apple, but it desperately needed a follow-up act. 

Then came the iPod.

To be fair, the original iPod wasn't an immediate hit. First, it was expensive. Second, it required FireWire, which meant you could only use it on a Mac. In fact, a Windows-compatible version of iTunes, the software you needed to sync your music to an iPod, wouldn't come out until a year later

Steve Jobs, famously, was against Apple making iTunes available on Windows, but once it did, sales took off. Millions of people who previously thought of Apple as a maker of quirky computers for nerds and enthusiasts suddenly saw the company as cool. There were colorful ads with silhouettes wearing white earbuds everywhere. Compared with the competition, the iPod was better in basically every way.

In six years, by 2007, the company had sold 100 million iPods. That year, of course, Jobs stood on a stage and introduced the iPhone. The iPhone, of course, is the reason the iPod died, even if it took a while. Apple made maybe the most important decision of any company when it was willing to cannibalize its most successful product for the sake of its future. That future worked out pretty well. Today, the iPhone has made Apple the world's most valuable company

This brings us to maybe the most important aspect of Apple's announcement. As critical as the iPod was to Apple 21 years ago, it's mostly irrelevant today. No one buys iPods unless they collect vintage electronics at this point. Partly that's because no one is downloading individual music tracks to sync to their devices. Everyone just uses streaming services.

For that matter, everything you could do with an iPod is better on an iPhone. It's the one device to rule them all.  

Despite the fact that for millions of people, the iPod was the thing that introduced them to Apple, keeping it around purely for the sake of nostalgia doesn't make much sense. Apple is the iPhone company now. You have to give the company credit for being willing to let go of what, for 21 long years, has been one of its most endearing products.