A netbook is a laptop computer designed primarily to be extremely cheap and extremely portable. As a result, these computers are significantly underpowered compared to the standards of other computers being produced at the same time; however, they are more than sufficient for simple Internet browsing, digital document production, and lightweight computing tasks.
Netbooks are a slap in the face to companies that have a business model based around stronger and stronger computers, producers of dedicated word processor devices, and people who can't understand the concept of enough computing power. They sit as a taunting opposite to giant gaming rigs, 40" widescreen monitors, and ENIAC. They are the opposite of conspicuous consumption; instead, they stand as conspicuous minimalism, a visible statement to others that you are using all the computer you need and no more.
Netbooks are very nearly disposable computers. I use mine at malls, crowded concerts at a coffee shop by one of my favorite bands, and outside at the city park. I would not consider taking my Tablet PC any of these places out of fear of damage; the computer was definitely not free, but it was sufficiently inexpensive that I am willing to take more risks with it.
Netbooks were heavily inspired by Web 2.0 and the advent of online word processors and other assorted office applications, Skype, and the wide availability of wi-fi access points. They become a highly convenient personal terminal, and the applications available online that use the strength of remote servers make up for the relative lack of strength of the computer.
That said, my Acer Aspire One was about half as expensive and twice as strong as the Gateway notebook I started college with five years ago, and it's running the same OS and similar applications. Despite how it compares to the specs of a more mainstream modern computer, it feels quite peppy.
In an example of everything2 costing people significant amounts of money, I bought my netbook mostly so I could try to keep up with THE IRON NODER CHALLENGE a bit while waiting three hours for a concert to start. (I wanted a good seat.) I did not actually compose any nodes during that time. I did, however, have a large number of people call it cute.