Pharmacies or retail stores are the ones who supply the medicines/drugs to the end customers. The pharmacies place their order with stockists/sub-stockists. This is commonly referred to as Tertiary sales. Medicines may be classified as prescription based and over the counter (OTC) ones. Prescription based medicines require a doctor's prescription before a patient can buy them. OTC are the ones which can be sold by even retails stores (examples can be cough tablet, band-aid, and so on).