A work breakdown structure involves breaking a project down into a series of smaller tasks.
A work breakdown structure must clearly identify each task and include an estimated duration. A task or activity is any work that has a beginning and an end and requires the use of company resources such as people, time, or money. Examples of tasks include conducting interviews, designing a report, selecting software, waiting for the delivery of equipment, or training users. Tasks are basic units of work that the project manager plans, schedules, and monitors — so they should be relatively small and manageable.
In addition to tasks, every project has events, or milestones. An event or milestone is a recognizable reference point that you can use to monitor progress. For example, an event might be the start of user training, the conversion of system data, or the completion of interviews. A milestone such as Complete 50 percent of program testing would not be useful information unless you could determine exactly when that event will occur.