Computer multitasking is the process of more than one program being executed by a computer at the same time. Early in the history of computing, multitasking was almost unheard of, and for decades was relegated to high-end mainframes and unavailable in personal computing. As technology advanced, multitasking became available and quickly evolved into the industry standard for personal computers. As of 2011, even devices such as smartphones are often capable of multitasking, allowing users to surf the Internet and stream music at the same time, for instance.
When computer multitasking was in the early stages of development, it was called time-sharing, a term which referenced the way multiple programs or processes shared the power of the CPU. Fairly early on, this term was supplanted by the contemporary term multitasking, although in its earliest versions, multitasking was not true multitasking but a rapid switching between applications that seemed simultaneous. Modern computers with only one processor are capable of seeming to perform multiple tasks simultaneously by using this technique.
Computers with multiple processors have two or more separate processors that are linked together. These systems, which have become more common and more advanced during the early 21st century, are capable of true multitasking, although in practice, there is no observable difference, aside from improved performance, in the way these systems work compared to single processor systems. The multiple processors allow many different programs to run at the same time, however.
System memory still limits computer multitasking. Computer performance is dictated by processor speed, but the number of programs that a given processor can run at one time is also limited by the amount of system memory these programs occupy. A technique called memory switching allows for the system memory to be accessed by whatever program is running at the moment on single processor systems or to be delegated as needed on multiple processor systems.
It is said that true computer multitasking is affecting the way people live, work and use their computers, and in some ways this is certainly true. Multitasking allows one to stream music from an Internet radio service while researching and writing a paper at the same time. The limitations on human abilities to multitask will ultimately limit the ways in which individuals can utilize the power of modern computers to multitask, however. Humans have limited ability to concentrate on multiple tasks or activities, making it difficult to interact with more than one software program at a time.