In honor of Mashable's five-year anniversary, this series is supported by IDG. Customers are talking about your brand and products — find out what they are saying with IDG Social Scout.

Five years ago, YouTube was just getting started, MySpace was the most popular website in the U.S., and Facebook was still limited to college and high school students. Mobile was mostly an after-thought, as we were still more than a year away from the introduction of the iPhone and the idea of an app store. And “widgets” were just starting to emerge as a way to integrate third-party apps on a website (Newsweek would declare 2007 to be “year of the widget” in a late 2006 article).

Fast forward to today and the sites we use and the way we use them have shifted dramatically. Facebook is closing in on Google as the Web’s most trafficked site. There are hundreds of thousands of mobile applications that users access across a variety of smartphones, and social media is increasingly being consumed and produced on the go. And “Like” buttons have become the new form of social currency for publishers around the world.

How did we get to this point? Here’s a quick look back at the last five years in social media.

The News Feed Brings It All Together

In late 2006, Facebook introduced the news feed – a controversial concept at the time (incidentally, there are many parallels between it and Facebook’s most recent privacy issues) that has since become perhaps the most important and oft-imitated feature in social networking.

It’s hard to remember life before the news feed, but it consisted mostly of visiting your friend’s profiles, making wall comments and perhaps maintaining a photo gallery. For Facebook, this innovation (and a lack of innovation by then leading social network MySpace) is the one that established the service’s utility and has been at the heart of its expansion since — showing you at a glance what your friends are up to on Facebook and around the Web.

Nowadays, whether it’s Twitter, Foursquare, Flickr or yes, MySpace, the experience very much centers around seeing the most recent updates from your friends, in reverse-chronological order.

Video Emerges as Social Media’s Perfect Compliment

A few months before the birth of Mashable, YouTube made its debut on the Web in February 2005, making an unprecedented ascent into the mainstream consciousness. By December of that year, it had already become the most popular video site, and by July of 2006, it was serving 100 million video views per day (today, it serves more than 2 billion views daily). Then, in October, Google bought YouTube for a whopping $1.6 billion, just 18 months after the site launched.

At the end of last year, I declared YouTube the top social media innovation of the decade, as it has come to embody so much of what we now know as social media, from highly shareable content to citizen journalism to the ability of anyone with a camera to claim their 15 minutes of fame.

Social Networks Spread Their Wings

In early 2008, a new battle in the social media space emerged – the battle over portable identity. While OpenID had long promised a single sign-on for third-party websites, Facebook, MySpace and Google started to realize that your social networking profile had potential to be used as your identity across the Web, while at the same time enabling publishers to make their sites more social.

Facebook Connect emerged, as did Google Friend Connect and MySpaceID. Eventually, as Twitter’s popularity grew, they also got in the game. Today, Facebook Connect – which has evolved into the Facebook Open Graph – is used by hundreds of thousands of websites that can add simple copy and paste code to let their visitors “Like” stuff; “Likes” that are then pushed back into the Facebook News Feed. MySpace and Twitter ultimately hooked up with Google Friend Connect, which is now in use on some 9 million sites.

Mobile Makes Social Indispensible

While there’s been a running joke that it was going to be “the year of mobile” for about a decade, it’s only within the last few years that smartphone use has exploded, and along with it, use of social media while not in front of a computer.

According to data published earlier this year, 30% of smartphone users now access social networking sites from their phone’s web browser – and that doesn’t even take into account people who download apps on their iPhone, Android, BlackBerry or other devices.

Thanks to increasing mobile broadband speeds, video is also going mobile. YouTube now serves up 100 million videos to mobile devices each day, and with more and more new phones offering video capture capabilities, we’re also seeing smartphones become an important part of content production.

What’s Next?

Now that we’ve established where we are – a social ecosystem that’s moving beyond the walls of individual sites to mobile devices and third-party applications – the question is: what’s next? Over the next month, we’ll be exploring some of the past five years more in-depth, and concluding with a look at what the next five years hold. Stay tuned to Mashable as we celebrate our five year anniversary!

Series supported by IDG

In honor of Mashable's five-year anniversary, this series is supported by IDG. Customers are talking about your brand and products — find out what they are saying with IDG's brand listening services. With IDG Social Scout you can listen to your prospects’ real-time conversations and understand the nature and sentiment of the dialogue. This information is key to help develop marketing messages and content that resonate with your audience. Learn more about how IDG Social Scout can help you by clicking here.

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Image courtesy of iStockphoto, AndrewLilley