Under Settings > Projects section, you will see a set of Default fields appear at the top in the blue shaded box. A Blue star denotes a Mandatory field.
You can add custom fields of your choice by clicking on the ADD CUSTOM FIELD button. All custom fields will appear below the default fields.
When adding a custom field, you can choose from 7 different field types. Click on the star icon to mark any field mandatory:
Some common examples of custom Project fields used are Job Number, Phase, Division Code, Project Number, Type of Work, Contract Value, Owner, Units, City, State...
To learn more about the Settings section click here.