Operating System (OS for short) is responsible for coordinating the management and sharing of computer resources. No operating system is not possible, three operating systems on the market today, device-independent dominant Windows (Microsoft), Mac (Mac / Apple) and Linux (Linus Torvalds and his partner) are running. The current Windows operating system is the best graphical user interface to improve the menus in the Start menu and click search for the Windows taskbar. This easy-to-use features allow customers to easily with the device, simple instructions. This system is known as a very stable and is characterized by high security protected. These are the anti-phishing filters that warn the user if an unauthorized person tries to use the site. He has also e-mail, Windows Defender, which preventing suspicious programs, advanced firewall, automatic backup and block encryption / decryption. This software allows quick access to local networks and the Internet. High-speed data loading and unloading can be achieved. Multimedia features such as video and audio is always a lot of Windows OS.The biggest drawback of the Windows operating system, the demands on the IT system. You must have a computer with a very large storage capacity, the need for graphics cards 128-256 MB free hard disk space for a minimum of at least 20 GB of memory (RAM) 2 GB. Windows operating systems are usually expensive. You may need to offer their latest software update, or to buy the new operating system to keep pace with technological developments advances.Macintosh operating system called Mac OS. And “less susceptible to infiltration and damage, such as malicious malware than Windows. This system is only sold in computer stores, but it is used only for Apple computers. For this reason, the Mac OS pricey.The units equipped with the Linux operating system for stability and durability to withstand long been known to use. This system rarely crashes. If this happens, usually, it does not hurt their computer programs. You can even older devices, such as a Pentium 100, 16MB RAM, and only 1 gigabyte. You can still use the outdated computer programs for various applications are compatible with Linux. The safety devices are effective because the developers can immediately correct deficiencies, the operating system can have.However, Linux has many disadvantages. First, many people do not know this software. Therefore it will take some time to learn how to act. Second, there are many programs for office software that runs on Linux. Third, we need professionals to work in the computer operating system, he said. Finally, computer programs that do not come with Linux software. Why can not act, and that properly.In operating system choice, should the accessibility and availability of support services .