You can operate with one company or many companies according to what will best fit your needs.
Read this chapter for general information about companies and specific minimum and advanced requirements for setting up a new company.
Company Data
Once a company is created, a folder is automatically created for the company and is given the name of the three-character company code. The software will store all the information for that company in this folder and most of the file names will begin with the three-character company code.