A project is simply a collection of simple joints and utility joints that can be saved into a single file on the hard disk. This is useful because utility joints rely on other simple joints to be open in order to have a joint to modify or combine. If you are using utility joints, you most likely will want to save your work as a project instead of saving each joint individually. When you open a project, each joint is reopened in the same state as when it was saved. Once open, each joint is treated as an individual edited joint. Projects can be reopened using the "File - Open Joint/Project" menu item.

A project can also be a convenient way to manage a collection of joints that are related to a particular job.