In SAP MM, material types are the materials which are having the similar attributes are categorized together and assigned to a material type. It is a classification of allowed material into material types based on attributes.
In material master, material type controls the following functions
1.Number range assignments i.e. External or Internally.
2.Field selections i.e. which fields are mandatory, optional, hide and display.
3.Quantity and values basis
4.External procurement or internal procurement
5.Which value classes are to be allowed

The important material types in SAP as follows