The word 'netbook' is a word created from 'Internet' and 'Notebook' and refers to a type of portable computer that is smaller than an ordinary notebook and is designed for wireless access to the Internet.
(Dell Inspiron Mini 9 Netbook)
Netbooks are mainly used browsing the web and e-mailing and they rely to a large extent on the Internet to provide remote access to web-based applications. They are designed more and more for so-called 'cloud computing' i.e. computing which requires less powerful computers.
At this moment in time netbooks generally run under either Windows XP or Linux and are not suited to bloatware such as Windows Vista (but then, what is?)
Netbooks currently range in size from under 5 inches to over 13 inches, although it is not clear is size matters here either. They usually weigh between 2 and 3 pounds (around 1 to 1.5 kg) and are generally a lot cheaper than normal laptops and notebooks. Although, as with everything in computing, prices are constantly changing.
In early 2009, the definition of a netbook was a "notebook computer with a low-powered x86-compatible processor", a small screen (under 10 inches), a small keyboard, wireless connectivity, and weighing less than 3 pounds 1.3 kg). Netbooks also have no optical disk drive.
(Samsung NC20 Netbook)
Netbooks make use of online applications and services, thus obviating the requirement for powerful hardware on the netbook itself. Hardisks and optical disc drives are often the first devices to be dumped in order to make the netbook smaller. Netbooks therefore rely on solid-state storage devices with no moving parts, which use less power and are lighter whilst at the same time being more robust and hard-wearing. Application software is usually downloaded from the Internet or uploaed for USB drive. You can also add an external IDE drive with a USB-to-IDE converter if you so desire.
All netbooks support Wi-Fi wireless networking and many of them can be used on cellphone networks with data capability.