The iPod Touch (stylized, trademarked, and marketed as iPod touch), is a portable media player, personal digital assistant, and Wi-Fi mobile platform designed and marketed by Apple Inc.
The iPod Touch has a slim rectangular shape with rounded edges, with a glass multi-touch display covering most of the top surface and a physical home button off the touchscreen. The display functions similarly to the multi-touch trackpad as implemented in Apple's current line of laptop computers. The touch and gesture features of the iPod Touch are based on technology originally developed by FingerWorks. On February 5, 2008, a 32 GB version was added in addition to the 8 and 16 GB versions. On September 9, 2009, a 64 GB version was added and the 16 GB version was removed from the line-up. Improved graphics were also added to the new 64GB and 32GB devices.
Source: Wikipedia, iPod Touch, available under the CC-BY-SA License.