Primitive types within ASN.1 are those types that are not constructed or cannot be broken down into more primitive types. They correspond to the normal data types encountered in many programming and data definition languages.

The term primitive type should not be confused with primitive encoding as defined in the BER standard. Some primitive types, such as BIT STRINGs, can actually be encoded in a constructed manner. However, in this case, all of the components must be of the same type as the constructed BIT STRING.