In computing, a task is a unit of execution or a unit of work. The term is ambiguous; precise alternative terms include process, light-weight process, thread (for execution), step, request, or query (for work). In the adjacent diagram, there are queues of incoming work to do and outgoing completed work, and a thread pool of threads to perform this work. Either the work units themselves or the threads that perform the work can be referred to as "tasks", and these can be referred to respectively as requests/responses/threads, incoming tasks/completed tasks/threads (as illustrated), or requests/responses/tasks. Terminology In the sense of "unit of execution", in some operating systems, a task is synonymous with a process, and in others with a thread. In non-interactive execution (batch processing), a task is a unit of execution within a job, with the task itself typically a process. The term "multitasking" primarily refers to the processing sense – multiple tasks executing at the same time – but has nuances of the work sense of multiple tasks being performed at the same time. In the sense of "unit of work", in a job (meaning "one-off piece of work") a task can correspond to a single step (the step itself, not the execution thereof), while in batch processing individual tasks can correspond to a single step of processing a single item in a batch, or to a single step of processing all items in the batch. In online systems, tasks most commonly correspond to a single request (in request–response architectures) or a query (in information retrieval), either a single stage of handling, or the whole system-wide handling. Examples In the Java programming language, these two concepts (unit of work and unit of execution) are conflated when working directly with threads, but clearly distinguished in the Executors framework: IBM terminology IBM's use of the term has been influential, though underlining the ambiguity of the term, in IBM terminology, "task" has dozens of specific meanings, including: A unit of work representing one of the steps in a process. A unit of work to be accomplished by a device or process. A process and the procedures that run the process. A set of actions designed to achieve a particular result. A task is performed on a set of targets on a specific schedule. A unit of computation. In a parallel job, two or more concurrent tasks work together through message passing and