Project Dependencies refer to a suite of relationships between objects and elements of a project such that one of the objects/elements cannot begin or be completed until one or more other objects/elements have occurred, begun or completed. They define certain conditions, events and rules that manage the behavior of project objects and elements as to each other.
Dependencies in a project can be applied to the following objects and elements:
Each of the listed objects/elements can be dependent on each other in the same project. Project dependencies establish high-level relationships between all objects/elements. At lower levels (e.g. task level or milestone level) project dependencies are usually specified with additional conditions and rules that identify the behavior of objects/elements at every level.
Work breakdown structure (WBS) serves as a high-level hieratical model of project dependencies. Meanwhile, lower levels of WBS may have certain dependencies that are particular and specific to those levels only. Usually work packages from one and the same level of WBS are closely dependent on each other but they are not related to work packages from other WBS levels.