Today, there are many computer categories. A(n) is the category for the world's fastest computers. computers are large, expensive devices capable of simultaneously processing data for thousands of users. Computers used by Google and Web service providers are classified as. Personal computers come in several varieties. A(n) computer fits on a desk, runs on power from an electrical wall outlet, and can be housed in a horizontal case or vertical case. Three categories of portable computers include tablets, smartphones, and clam-shell style computers. Selecting a digital device requires consumers to select a platform based on form factor and operating system. MacOS is the operating system that runs on Apple laptops and computers. The operating system for iPhones and iPads is . The operating system from Microsoft runs on laptop and desktop PCs, whereas a derivative version is designed for tablets and phones. The open source community produces Linux for desktops and servers. This family of operating systems also includes Chrome OS, and , which is popular for tablets and smartphones.