Glossary: Staff
Staff is a type of resource, representing people who work on the project.
Staff units are measured as percentages. A person who is fully available to the project has a units value of 100%; someone who is spending part of their working hours on other projects would have lower available units. Note that this is not the same as having fewer working hours (which can be set in the calendar view), or being less efficient (which can be set in the Resource Information inspector).