When making a Custom Field, you also chose a Mode for the field. Continue reading below, as we go through all the modes for Custom Fields.
The Standard mode is:
Visible
Can be changed manually and through data import and API
Optional
The Mandatory mode is:
Visible
Can be changed manually and through data import and API
Mandatory to fill out
The Protected mode is:
Visible
Can ONLY be changed through data import
Optional
The Read only mode is:
Visible
Can ONLY be changes through data import and API
Optional
The Hidden mode is:
Invisible
Can be changed manually and through dataimport and API
Optional