Caffeine

Patent Pending Caffeine (/kæˈfiːn, ˈkæfiːn, ˈkæfiːɪn/) is a central nervous system (CNS) stimulant of the methylxanthine class of psychoactive drugs.[7] It is the world's most widely consumed psychoactive drug, but unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. It is a bitter, white crystalline purine, a methylxanthine alkaloid, and thus closely related chemically to the adenine and guanine contained in deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).