This technique shows how processes or objects interact with each other in the context of specific scenarios.

There are three key notational elements:

• A life line: A life line demonstrates the life span of an object that is modeled for a scenario.
• An activation box: An activation box shows the time period that an operation is executed in.
• A message: A message shows the interaction between two objects. 

This technique shows the sequence of actions in the order that they occur and is a great visual way to ensure that a logical and accurate process is followed.