Task
A task is simply a unit of work: something that needs to be done.
A task usually as a well defined algorithm or method, and parameter and signature. It depends on little external information, and may be run at an arbitrary moment: although, it is expected to be run as soon as possible.
It is usually expected to take some time to complete.
Task are handled by a task manager, or a job queue. One process insert the tasks, secondary servers process the tasks and finally, one last process make the result of the task known.