The Full Form of AON is Activity On Node.

Activity-on-node is a project management term that refers to a precedence diagramming method which uses boxes to denote schedule activities. These various boxes or “nodes” are connected from beginning to end with arrows to depict a logical progression of the dependencies between the schedule activities. Each node is coded with a letter or number that correlates to an activity on the project schedule.

Typically, an activity-on-node diagram will be designed to show which activities must be completed in order for other activities to commence. This is referred to as “finish-to-start” precedence – meaning one activity must be finished before the next one can start. In the diagram below, activities A and D must be done so that activity E can begin. It is also possible to create other variations of this type of diagram. For example, a “start-to-start” diagram is one in which a predecessor activity must simply be started rather than fully completed in order for the successor activity to be initiated.