But in 2006 Facebook opened its doors to anyone over 13 with a valid e-mail address. Now, with about 300 million members worldwide, it's bigger than many countries.
Twitter, the social networking site that lets users broadcast 140-character messages, also experienced a turning point that fall when its founders reacquired the struggling site from investors.
Millions of people all over the world use social networking sites like LinkedIn, Bebo and Orkut, to communicate with friends of family, play games, mobilize for civic action and more.
In April 2003, scientists announced that they had sequenced the entire human genome two years ahead of schedule.
The 13-year international project set out to identify the 20,000 to 25,000 genes in human DNA. When the International Human Genome Sequencing Consortium announced that they had finished sequencing the human blueprint, they said the task had been likened to splitting the atom or going to the moon.
The project has helped shed light on human migration, common diseases, new energy sources and many other scientific fields.
Larry Page and Sergey Brin incorporated Google in 1998, and in 2004 the company sold shares to the public for the first time, solidifying search as a way of life.
Yahoo, Microsoft's MSN, Ask.com and now Bing also help users search the Web, but Google still owns about 65 percent of the search market.
And it isn't just a noun. To search for information about potential dates, future employees and even themselves, users commonly "Google" to obtain all kinds of information from the Web.
According to the Pew Internet & American Life Project, in 2002 about one-third of all Internet users used search engines daily. In 2008, the number rose to just under one-half of all users.
When Nintendo launched the Wii and Wii Sports in 2006, it changed the way video games were played.
Instead of sitting on the couch with a remote control in their hands, players were pulled into the action, using a wireless controller to simulate actions such as playing tennis and boxing.
The Wii has been touted as more than a game. The system has been used to teach school children music and help people lose weight.
It was the most anticipated tech events of the year.
On June 29, 2007, thousands of people waited in seemingly-endless lines to buy Apple's highly-hyped iPhone. In 74 days, Apple sold 1 million of its smart phones.
More than 40 million users access the Internet from iPhone and iPod touch models. Millions of others go online with BlackBerries and other mobile devices.
Mobile phones used to do one thing only: make phone calls. But now consumers use their handhelds to access the Web, send and receive e-mails, play games, take pictures and watch video.
And with the growth in mobile applications, like those in Apple's App Store and the Android Marketplace, the list only continues to grow.
Apple's App Store alone holds more than 100,000 applications that let users doing everything from play games and track stocks to run background checks and find public rest rooms.