A task is a work item that tracks a combination of three elements: duration, work, and units. Duration defines the total length of time required to complete a given task, measured by a task's start and finish dates. Work defines the total amount of labor that is needed to complete a given task. Units defines the resource (or resources) assigned to complete a given task.

All tasks are scheduled using the formula Duration = Work / Units. You can determine which part of the forumula is calculated (or recalculated) by choosing a task type:

In addition to duration, work, and units, many tasks also have dependencies and constraints. Some tasks are summary tasks, which contain rolled-up information from all of the child tasks.