Qubes OS is a security-oriented operating system (OS). The OS is the software that runs all the other programs on a computer. Some examples of popular OSes are Microsoft Windows, Mac OS X, Android, and iOS. Qubes is free and open-source software (FOSS). This means that everyone is free to use, copy, and change the software in any way. It also means that the source code is openly available so others can contribute to and audit it.
Qubes takes an approach called security by compartmentalization, which allows you to compartmentalize the various parts of your digital life into securely isolated compartments called qubes.
This approach allows you to keep the different things you do on your computer securely separated from each other in isolated qubes so that one qube getting compromised won’t affect the others. For example, you might have one qube for visiting untrusted websites and a different qube for doing online banking. This way, if your untrusted browsing qube gets compromised by a malware-laden website, your online banking activities won’t be at risk. Similarly, if you’re concerned about malicious email attachments, Qubes can make it so that every attachment gets opened in its own single-use disposable qube. In this way, Qubes allows you to do everything on the same physical computer without having to worry about a single successful cyberattack taking down your entire digital life in one fell swoop.
Moreover, all of these isolated qubes are integrated into a single, usable system. Programs are isolated in their own separate qubes, but all windows are displayed in a single, unified desktop environment with unforgeable colored window borders so that you can easily identify windows from different security levels. Common attack vectors like network cards and USB controllers are isolated in their own hardware qubes while their functionality is preserved through secure networking, firewalls, and USB device management. Integrated file and clipboard copy and paste operations make it easy to work across various qubes without compromising security. The innovative Template system separates software installation from software use, allowing qubes to share a root filesystem without sacrificing security (and saving disk space, to boot). Qubes even allows you to sanitize PDFs and images in a few clicks. Users concerned about privacy will appreciate the integration of Whonix with Qubes, which makes it easy to use Tor securely, while those concerned about physical hardware attacks will benefit from Anti Evil Maid.