Tobacco is the name of a plant. The leaves have a chemical in them. The chemical is called nicotine. Nicotine is a drug. It can change the way that people feel. People have found different ways to use tobacco.
Have you seen people smoke? They burn dried tobacco leaves and breathe in the smoke. They might smoke tobacco in a pipe. They might smoke a cigar or a cigarette.
Sometimes people like to chew tobacco. Some like to "dip" it. That means they can put a bit between their gum and lip.
Some even like to use snuff. That is powdered tobacco that is sniffed up the nose. That could make you sneeze! Achoo!