A meteor shower is a celestial event in which a number of meteors are observed to radiate from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth's atmosphere at extremely high speeds on parallel trajectories. Most meteors (or colloquially shooting stars or falling stars) are smaller than a grain of sand, so almost all of them disintegrate and never hit the Earth's surface.
The most visible meteor shower in most years are the Perseids, which peak on August 12 of each year at over 1 meteor a minute. The most spectacular meteor shower is probably the Leonids, the King of Meteor Showers which peaks on a day near 17 November. Approximately every 33 years the Leonid shower produces a "meteor storm", peaking at rates of thousands of meteors per hour. (From: Wikipedia)