Wubi

Wubi (Windows-based Ubuntu Installer) is an installer of the Ubuntu Linux operating system, as well as Kubuntu, Xubuntu, Lubuntu and other official flavours, designed to run in Windows. It can be used to install Ubuntu as a regular application. There is no need to repartition the hard disk - during the installation process a new folder is created on a normal Windows partition, and Ubuntu is placed there inside a large disk image file.

After installation, an additional entry appears in the Windows boot menu allowing you to choose whether to boot Windows or Ubuntu. With the help of Wubi, almost any Windows user can get a full Linux-based operating system without the risk of losing data while partitioning. Besides, Wubi allows you to uninstall Ubuntu from the Control Panel as an ordinary Windows program.

A warning: Wubi is no longer developed.

Wubi simplifies the process of installing and uninstalling Ubuntu Linux on a Windows system.

The Wubi program is essentially a web installer - it does NOT contain an operating system. After it is launched, the Ubuntu image is automatically downloaded from the Internet (several hundred megabytes of traffic) and installed; the download can be resumed. Besides, if you already have a disk with the Ubuntu operating system or its ISO image, Wubi can use it in its work - and you won't have to download the OS from the network again. Wubi was dropped from the official Ubuntu download page from release 13.04 onward. It does not support UEFI computers, and hibernation is not available in a Wubi installation. Wubi is free, open-source software released under the GNU GPL.