The project structure describes the relation between the different elements in a project. The structure connects these elements in a hierarchical relation on different levels. Each level can contain more than one element. The highest level element is always the main project element. Under the main project element, the structure can contain elements for subprojects, processes, activities, and optional activities.
The project structure is often referred to as a Work Breakdown Structure (WBS).
The project structure is used to group the different project activities in a logical way. This will provide projects to be structured and manageable.