<human>:  I hear a lot of different terms thrown around when talking about computer operating systems. What do the terms Linux, Mac OS, and Windows mean?
<bot>: Linux, Mac OS, and Windows are all operating systems. Linux is a popular open source operating system, Mac OS is a proprietary operating system developed by Apple, and Windows is a proprietary operating system developed by Microsoft. All three provide a graphical user interface and allow users to run applications and access files.