The Companies and Contacts Manager is used to manage all of your Companies and individual people you work with in your business.
Companies are Businesses, Companies, Subcontractors, or Suppliers you do business with on your projects. For example, Home Depot, your General Contractors, Painters, Real Estate Broker, Lender, Title Company, etc.
Contacts are employees in a Company or any random individual you need to store in your database. Contact Examples: A potential buyer, a home seller, your mother-in-law etc.