Work performed by people, equipment, technologies, or facilities. Activities are usually described by the action-verb-adjective-noun grammar convention. Activities may occur in a linked sequence and activity-to-activity assignments may exist.

1. In activity-based cost accounting, a task or activity, performed by or at a resource, required in producing the organization's output of goods and services. A resource may be a person, machine, or facility. Activities are grouped into pools by type of activity and allocated to products.
2. In project management, an element of work on a project. It usually has an anticipated duration, anticipated cost, and expected resource requirements. Sometimes major activity is used for larger bodies of work.