1. LINUX
1.1. PROS
1.1.1. broadest driver support
1.1.2. numerous options for customization
1.1.3. more secure than OS X and Windows
1.1.4. everything is free
1.1.5. full access to the free open source library
1.1.6. easier patch management
1.2. CONS
1.2.1. latest hardware doesn't support Linux
1.2.2. not for the non-technical
1.2.3. doesn't support MS office
1.2.4. limited vendor support
1.3. MOST POPULAR
1.3.1. Ubuntu
1.3.2. Fedora
1.3.3. openSUSE
2. OS X
2.1. PROS
2.1.1. simpler to use
2.1.2. allows better content creation
2.1.3. UNIX base allows more security
2.1.4. more stable and powerful than Windows
2.2. CONS
2.2.1. overpriced
2.2.2. poor remote support
2.3. MOST POPULAR
2.3.1. El Capitan
2.3.2. Yosemite
2.3.3. Maverick
2.3.4. Mountain Lion
3. WINDOWS
3.1. PROS
3.1.1. easy access
3.1.1.1. support
3.1.1.2. hardware
3.1.1.3. driver
3.1.2. majority of PC's today run on it
3.2. CONS
3.2.1. too much support needed
3.2.2. easy to hack
3.2.3. new versions can be poorly optimized
3.3. MOST POPULAR
3.3.1. windows 7
3.3.2. windows 10
3.3.3. windows 8
4. TYPES OF OS
4.1. multi user
4.1.1. multiple users at same time
4.2. multi-processing
4.2.1. supports more then one computer processor
4.3. multithreading
4.3.1. extends the idea of multitasking into applications