Projects are a way to group together tasks that need to get done in order to accomplish a goal.  Unlike Smart Groups, they are not tied to tags and they are Area specific.  This is a very exclusive group, a task cannot belong to more than one project.  All tasks associated with the project will take on the Project’s Area, even if the task was not assigned an Area during creation.  This is an easy to way to move a large amount of tasks into an Area.