A bootable live USB image of Ubuntu 12.04.1 64-bit desktop edition. This image can be written to a USB drive or flash media such as an SD card to boot from and install or preview Ubuntu Linux.
For Windows users a tool such as Win32 Disk Imager (https://launchpad.net/win32-image-writer) or USB Image Tool (http://www.alexpage.de/usb-image-tool/download) can be used to write the image to a media device.