I am seeking information about how to add field in any shapefile that has no
"The selected field is an inherent field of the feature class managed by the geodatabase. For example, in a polygon feature class, there are four fields that are unavailable for editing: OBJECTID, Shape, SHAPE_LENGTH, and SHAPE_AREA."
For example, If you have a polygon that shows grassland and it doesn't have the field it needs to calculate geomtery such as an acre.
Is there a website that explains for polygon, lines, points, etc that an user can decide to select which one ifor a proper field.
I have seen this site but it doesn't really help me much.
https://desktop.arcgis.com/en/arcmap/10.3/manage-data/geodatabases/arcgis-field-data-types.htm
Let me know if you need an clarification here.