Project scheduling is a rich field, but in a nutshell: projects consist of activities that consume resources and have associated costs. An activity can be almost anything, although typically, someone does something. Resources are often people’s labor, though they can also be machines, facilities, etc. The start of one activity may depend on the completion of one or more other activities. Given that everything can’t happen at once, a project winds up being a succession of activities that consume time, resources, and money.