The free software movement is a software movement which aims to improve the user's rights on software and reducing proprietary (non-free) software through the use of operating systems such as Ubuntu. The movement is generally signified through open source software such as Mozilla Firefox, Mozilla Thunderbird, FileZilla and open source operating systems such as Linux and ReactOS. The movement is against non-free software that restricts the user's rights. Examples of non-free software include Microsoft Windows, Adobe Acrobat and UltraEdit.