A multitasking operating system is any type of system that is capable of running more than one program at a time. Most modern operating systems are configured to handle multiple programs simultaneously, with the exception of some privately developed systems that are designed for use in specific business settings.
With older examples of the multitasking operating system, managing two or more tasks normally involved switching system resources back and forth between the two running processes. The system would execute tasks for one, freeze that program for a few seconds, and then execute tasks for the other program. While this approach did create a short time lag for the operator, this lag was usually no more than a few seconds, and still offered considerable more efficiency than the older single-task operating system.
Over time, popular incarnations of the multitasking operating system were developed that used a different approach to allocating resources for each active program. This created a situation where virtually no time lag occurred at all, assuming that the equipment driving the system had adequate resources. For the end user, this meant the ability to perform several tasks simultaneously without any waiting for the system to release or redirect resources as each task completed in turn.
The typical multiple operating system requires more resources than the simple operating systems that were common for desktop computers in the late 1970s and early 1980s. Newer systems require platforms with a considerable amount of random access memory (RAM) as well as other type of virtual memory. If the resources are not available to drive the various applications that are open and being executed, the system may slow to a crawl, or possibly even shut down an application or two if that is the way the system is configured to prevent overload.
Today, most desktop, laptop, and netbook operating systems function with some type of multitasking operating system. Even equipment such as automatic teller machines or ATMs still make use of some type of multitasking system, using a series of programs to check balances and execute the requests made by users. There are also examples of movie ticket stub systems that are able to perform several tasks at once, including posting receipts for tickets purchased, even as the system generates and dispenses the purchased tickets.