Drugs

Morphine is an alkaloid that can be extracted from the plant papaver somniferum. It occurs naturally.

Diacetylmorphine (also known as "heroin") is synthesized using regular morphine and does not occur naturally.

So, heroin is one form (ester) of morphine that must be obtained via semi-synthesis by acetylating the base product, much like salicylic acid is acetylated to produce acetylsalicylic acid (also known as "aspirin").