Apart from the big commercial companies such as Microsoft and Apple- http://www.microsoft.com/ http://www.apple.com/ There is also numerous other free operating systems, such as Linux, BSD and Solaris. Distrowatch covers all the free OSes- http://distrowatch.com/
YES.
command- line
Almost all operating systems in existence today are more than capable of networking.
Most operating systems are designed for either 32-bit or 64bit CPU's.
There are many types of single user operating systems available today; they encompass the systems found on mobile phones and personal computers. Examples of popular single user, multitasking operating systems, for example, include Windows, Linux, and Mac OS X.
Almost every operating system that was ever created is still being used at least occasionally by someone.
1. Windows 2. Macintosh 3.Linux
Microsoft Windows Operating Systems (XP and VISTA) are the most heavily used today.
If by computer systems you mean operating systems, then: 1) Windows 2) Macintosh 3) Linux
No, they use picture based interface
If they decided to, all computer operating systems belong to Microsoft. That means no iOS from Apple, no Google chrome operating systems and many more. you decide. If that happens, what would a big corporation do with its money and what power will he have?
Despite being created by different software developers, most operating systems today are graphical-interface-oriented. Also, most of the OS's, including three of the most popular (Windows, Macintosh and Linux) support multitasking.