Many popular superstitions center around luck, including the belief that a horseshoe, crossed fingers or a rabbit's foot bring good luck to people. A horseshoe has seven holes, and seven is considered a lucky number. Other popular superstitions are based on the notion of bad luck, such as a black cat crossing a person's path or walking under a ladder.
Other pro-luck superstitions include that a four-leaf clover brings good luck because of its rarity, and that wearing jewelry bearing a birthstone is good luck. "Beginner's luck" is a term based on the notion that someone may have success, despite lacking experience, when attempting something new. Other bad-luck superstitions include the belief that Friday the 13th is an unlucky day and that stepping on a crack leads to negative circumstances.
Some superstitions are tied to specific events or occurrences. The belief that garlic and crosses repel vampires is perpetuated in many movies, books and television shows. Some people believe that when a person stares into a mirror for too long, the mirror captures their soul. Making a wish upon the first star at night or before blowing out birthday candles are other popular and often-practiced superstitions. Knocking on wood is supposed to protect a person from tragedy or disappointment after making a hopeful statement.