Digital computers are programmable machines that use electronic technology to generate, store and process data. Two terms, positive "1" and nonpositive "0," compose the data into a string. Data converted into binary numbers are measured in "bits." The string of 0s and 1s is called a "byte" when formed into a group. Digital speed and calculating power is measured in megaHertz, or millions of cycles per second, also known as "clock speed."
In 1937 at Bell Labs, George Stibitz invented the first calculator based on binary circuits to perform complex mathematical formulas. Stibitz's invention transformed computer science from analog to digital. With the advent of digital technology, scientists could customize a computer's operating functions by developing programming languages.
Technically, depending on how the terms "digital" and "computers" are defined, such devices as calculators, cameras, smartphones or any accessory with a microprocessing chip could be considered a type of digital computer. However, today digital computers are most commonly referred to as personal computers, also known as desktops and laptops. Dell, Hewlett-Packard and IBM are only a few of many companies manufacturing personal computers.
By broadening the definition of "digital computers," additional types may also apply. TechTerms.com states, "a 'minicomputer' is a powerful computer that can support many users at once. A 'mainframe' is a large, high-powered computer that can perform billions of calculations from multiple sources at one time. Finally, a 'supercomputer' is a machine that can process billions of instructions a second and is used to calculate extremely complex calculations."
The main hardware features for a desktop digital computer include the motherboard, hard drive, central processing unit (CPU), random access memory (RAM), graphics card and power supply. Hardware for laptops include all desktop features with the addition of a keyboard and monitor. The crucial software for both desktops and laptops is the operating system. As of 2009, the most popular are Microsoft Windows, Apple's Mac OS X Snow Leopard and Linux distro Ubuntu.
Digital computers have revolutionized the way people work, play and manage tasks. The U.S. Census Bureau released a report that stated, "72.3 million people used computers on the job in 2001. In 2002, software publishers generated revenue of $89 billion, and 99 percent of schools offered Internet access, up from only 50 percent in 1995. An estimated $156 billion online retail sales transactions occurred in the United States for 2003." These statistics demonstrate the overwhelming impact digital computers have on our lives.