Meteor shower
Also called: meteor, shooting star, radiant, ZHR, zenithal hourly rate.
A night with many shooting stars, when Earth passes through the dusty trail of a comet.
Meteors are grains of comet dust burning up 100 km overhead. In a shower they all seem to fly out from one point, the radiant (the Perseids from Perseus, the Geminids from Gemini). The ZHR — zenithal hourly rate — is how many you'd see per hour in a perfectly dark sky with the radiant overhead; real counts are lower, especially with moonlight or a low radiant.
At the eyepiece
No telescope needed: lie back somewhere dark, look about halfway up the sky (not at the radiant), and give it an hour. After midnight is usually best.
In AstroPilot
Tonight's “Coming up” lists meteor-shower peaks with the radiant's height for your location and how much the Moon interferes.