A disease or condition is considered rare if it affects fewer than one in every 2,000 people in the general population. There are currently about 6,000 known rare diseases, and new ones are being discovered on a regular basis in scientific literature. Word ‘Orphan’ is derived from the Greek term ‘orphanos’, which refers to a child who has lost one or both parents, as well as an adult who has lost a child. Orphan drugs are medications used to diagnose, prevent, or cure rare diseases that are life-threatening or disabling. They're called "orphans" because the pharmaceutical business has little interest in developing and marketing medications for a small proportion of patients with extremely rare diseases under normal market conditions.