A lottery is a contest where players buy tickets and have a random (and low) chance of winning. Finding true love and getting hit by lightning are often said to be as likely as winning the lottery.
A lottery can be a state-run contest promising big bucks to the lucky winners, or a lottery can also be any contest where the winners are selected at random. For example, some schools choose students by using a lottery system. Regardless of the type of lottery, a lottery works where there is great demand for something and only a limited number of winners.