Your company's directory
Your company's Directory is like a Rolodex, which would be a better analogy if people still knew what Rolodexes were. It's really just a place where you can collect contact information on people that you have worked with, or might work with in the future. These people do not have to be ProductionNext members -- you create them by entering their name, email address, phone number (if you have it), and some other information about them.
Building up your directory is a good thing because it makes it really easy to add people to a project -- just a few clicks. It also means that we can keep track of the casts and crew for all your projects, and prepare accurate call sheets for them. Plus, it's generally handy to have all that information in a single place.