Samsung 

Not many companies sell 55 million smartphones in a quarter. Samsung did, and it will probably do it again.

Galaxy S III

Samsung is hot in large part due to its top smartphone, the Galaxy S III. With over 18 million units shipped in the third quarter, and 30 million shipped in five months, it’s easy to see why.

iPhone 5

Sure, it was Time’s gadget of the year. But more importantly, iPhone 5 catapulted Apple back into the smartphone leadership position, at least in the U.S.

iPad Mini

We called it immediately: light, portable, awesome, and expensive. And it even looked better up close and person in our review.

But we had no clue it would become one of Apple’s best-selling iPads. And now that it’s probably going Retina in April/May, it’s just getting better.

YouTube

YouTube continues to be the online leader, by far, in online video with 800 million visitors and billion-view channels created by individuals and brands.

Despite getting the boot from iOS6, YouTube just continues to grow, with 25 times the video streams of its nearest competitor.

Twitter

2012 is the year that Twitter went mainstream, reaching 500 million users mid-summer and just recently announcing 200 million monthly active users.

And despite major new API restrictions that soured its relationship with developers, a very public spat with Instagram, and an evolving shift from social utility to media company, the company continues to grow and solidify its space in fast-breaking news.

Instagram

With a sale initially priced at almost $1.3 billion and an exploding user count, not even a tone-deaf terms-of-service change that spurred a class action lawsuit and a possible exodus of some users can keep Instagram off our winner list.

Google

Android is hot — 75 percent market-share hot. Search is still a massive strength for the iconic company that runs an ad 30 billion times each and every day.

And so Google makes over $100 million a day – and hits our list of hot companies in 2012.

ARM

With the vast majority of the chips in smartphones running ARM processors, ARM has people wondering whether the mobile juggernaut will challenge Intel for CPU dominance.

That’s still a stretch, but not nearly what it was just a few years ago.

Reddit

With 3.8 billion page views and 46 million unique visitors in October — double the previous year’s numbers — Reddit is continuing its torrid growth.

And it doesn’t hurt when the POTUS himself chooses your site to do an informal meet-the-people session — which required 60 dedicated servers.