The different decorations on each side of a coin might be used to decide things randomly. This is called "tossing a coin". A person can throw the coin into the air and catch it. You then look at which side is facing up. If the head is facing up it is called "heads", if the other side is facing up it is called "tails". Before tossing the coin someone has to decide what each side means. Tossing a coin can be a type of gambling, which is illegal (against the law) in some countries.