As the year draws to a close, most tech experts are agreeing that one of the biggest tech trends of 2009 was the social network. Sites like Facebook and Twitter, once the domain of techies and teenagers, went mainstream. Millions of non-technical users plugged into social networking this year.

As more people became involved, the content of many social network sites improved. Those involved in a cause found these sites to be a ready-made forum for discussion. Middle-aged people discovered the communication tools that are built into social networks. Many businesses also began using social network sites as a way to establish their brand and communicate with customers. This trend could continue and grow in 2010.

This month, Facebook announced that it now has 300 million users and is generating enough revenue to cover its costs. That makes Facebook the largest social networking site on the Internet. Analysts say this could lead to an initial public offering in the near future, though CEO Mark Zuckerberg is not committing to that happening anytime soon. Facebook was born in a Harvard dorm room 5 years ago and has now grown into one of the top Internet destinations, with membership tripling in the past year alone. Zuckerberg says the company is now exploring ways to boost performance and handle additional membership growth.