Heroin is a drug that comes from a flower, the opium poppy, which usually grows in Mexico, Asia, and South America. It’s very addictive and has been illegal in the United States since 1924. It can look like a white or brown powder or a sticky black “tar.” It’s also called horse, smack, junk, and brown sugar, among other names. One of the hallmarks of addiction is a person not being able...