Open-source software consists of programs and applications that are publicly available for download, sharing, and most importantly, modification. Anyone can review the code and enhance it for everyone else. The idea behind open-source software is increased exchange of information, more collaboration between software engineers, transparency during the development process, and rapid iteration and development of products. Since the entire process is open and public, software developers are judged only by their merits. Open-source software gives users more control and often more stability. Many open-source programs are also more secure, since a far larger number of people consistently examine the code. Examples of open-source software include the Firefox web browser, GIMP image manipulation software, and Ubuntu (a Linux operating system). Open-source software is different than proprietary software, where one person, a small team, or a specific company controls the exclusive rights to maintain and modify the code within a program. Only the original developers of the software can change what it does, how it looks, or fix any bugs. Users of the software (who are usually required to purchase it) must sign off on a user agreement. Examples of proprietary software include the Microsoft Office suite, Adobe Photoshop and Illustrator, and paid apps on the Apple app store.