The Revit family creation procedure includes the following properties :
Category: Revit families are grouped and separated by categories in content libraries. Examples of categories include doors, curtains, walls, furniture,etc.
Type: These are variations within a category. For example, in a door family there may be several types with different dimensions and properties.
Instance Property: This property specifies data for a specific instance of the family element. Any modification to an instance property will only affect that particular instance of the family. Continuing the example of a door family, an instance property can be the frame materials or the sill height.
Type Property: This property specifies data for all instances of the same family type. Changes made in a type property will affect all instances of that type. For example, thickness and width are both type properties in a door family.