I vividly remember Steve Jobs introducing the iPhone on January 9, 2007, a device he dubbed a touchscreen iPod, mobile phone and “internet communicator” all in one product. I immediately looked at my Motorola Razr with a burning sense of hatred. Now, with the benefit of hindsight, it’s pretty easy to say the iPhone launch was the most transformative event in the last 20 years of consumer technology. Even though the original model was lacking in a lot of important ways, its impact was so immediate and monumental that the history of consumer technology was instantly split into two eras: PreiPhone and Post iPhone.

Take the personal computer revolution, for example. Moving room-sized computers from research institutes into something a regular person could buy and use in their home was undoubtedly a huge advance, but there were multiple inflection points in the ’70s, ’80s and ’90s that helped usher in modern computing. The trinity of the Apple II, Tandy TRS-80 and Commodore PET 2001 in the ’70s represented the first wave, followed by the rise of the IBM PC and Macintosh in the ’80s. Things really took hold in the ’90s with the dominance of Microsoft Windows; the arrival of Windows 95 was a particularly transformative moment. In more recent history, the laptop became a viable and then dominant in the late ’90s and 2000s, which changed how most people think about computing. These were all events that moved the personal computing marketplace forward, but it’s hard to say one was more important than the others. It was more of a gradual rise and fall of various technologies that brought us to the modern era.

But the mobile phone market was completely reshaped by the iPhone, even if it took a few years for the effects to play out. Companies like BlackBerry, Palm and Nokia clung to the pre-iPhone conception of a smartphone for too long, focusing on business users and physical keyboards and not materially improving the software experience. Those companies are gone or irrelevant to mainstream consumers now. Palm’s introduction of its own webOS and Microsoft’s purchase of Nokia to push Windows Phone forward were reasonable efforts to challenge the iPhone, but they were far too little, too late. Hardware and software quality was hit or miss in both cases, but the main issue was that developers never embraced either platform, largely because consumers adopted iPhone and Android so quickly. The best iPhone apps usually never hit those devices, leading to inevitable doom.

On the other hand, Google and Samsung went all-in on Android almost immediately and quickly reaped the rewards of having an alternative to the iPhone. Android had enough similarities to iOS while also offering enough differentiation to capture a new part of the market. That’s particularly true internationally, where the massive variety of price points and devices was a huge advantage in markets where most people were priced out of Apple’s products. And given that Android arrived just a few months after Apple launched the iPhone App Store meant developers quickly started writing apps for both platforms, giving Android the support it needed. Essentially, everyone either followed in Apple’s footsteps or quickly went extinct.

It goes without saying that the iPhone reshaped a number of other businesses as well. The late aughts were awash with single-function gadgets, from obvious things like digital cameras, portable gaming devices and the iPod. (Also consider what phones have done to watches, paper calendars, lists and address books.) In the Post iPhone Era, consumer-grade digital cameras and portable music players are extremely niche — the iPhone’s camera is more than good enough for most people, and the iPhone itself quickly cannibalized the iPod.

Portable gaming systems are enjoying a bit of a resurgence, but the popularity of games on a phone that anyone can pick up and play is unmatched. If Nintendo’s Wii made its mark by offering casual gaming, the iPhone and the App Store quickly took that concept on the go. Both Call of Duty Mobile and Candy Crush Saga have peaked at about 500 million players, while Minecraft is the top-selling game of all time, with 300 million copies sold. Most AAA blockbuster titles don’t crack 50 million copies sold.

Moving from that Razr to an iPhone was a breath of fresh air. Watching YouTube and movies I had purchased via iTunes transformed my plane rides or commutes. Being able to browse real web pages and use a solid enough email client on the go made me more productive (and began my crippling information addiction). The “touchscreen iPod” felt like a futuristic and intuitive way to navigate my music library. It took until the iPhone 4 in 2010 for Apple to really focus on camera and image quality, but that didn’t stop people from shooting tons of photos and uploading them to Facebook. Even 2009’s iPhone 3GS took respectable enough snapshots and videos that my photo library started growing exponentially, and I’m glad to have a lot of those old, grainy shots from my late 20s.

And about a year after the first iPhone, the App Store blew open the doors on what was possible. Games, productivity tools, better messaging apps, social media, streaming music and everything else we associate with a modern smartphone quickly burst forth. Some people didn’t really consider the first iPhone a “smartphone” since you couldn’t install third-party apps, and Apple wisely saw the writing on the wall and fixed that glaring omission.

Whether all of the changes that followed the iPhone’s rise are a good thing is debatable. Having near-unlimited access to the internet at all times often feels like more than we can handle, and smartphones have enabled all kinds of digital abuse. Our privacy has gone out the window as these devices log vast amounts of data about our movements and desires and spending habits and search histories on behalf of the biggest companies in the world, who monetize it and try to keep us addicted. Steve Jobs almost certainly did not have all of this in mind when he pulled the iPhone out of his pocket in 2007, and the technology advanced so quickly we didn’t know what we were getting ourselves into.

The ramifications of all this will take decades to fully play out, and to some degree, many of us are already pulling back from the “always connected, sharing everything” mindset the iPhone enabled. The specter of government regulation, at least from the EU, coming for companies like Apple and Google is impossible to ignore, though it’s hard to imagine much happening to loosen their dominance in the near term. Regardless of what changes, there’s no doubt we live in a world where, thanks to the iPhone, the most important computer in people’s lives is the one in their pocket.

To celebrate Engadget's 20th anniversary, we're taking a look back at the products and services that have changed the industry since March 2, 2004.