Meteors are the visible trails left in the atmosphere by the entry of meteoroids - the IAU defines a meteoroid as "a solid object moving in interplanetary space, of a size considerably smaller than an asteroid and considerably larger than an atom".  This means meteors are small particles from space burning up as they plough into Earth's atmosphere.  When they actually survive to land on the Earth's surface, they are called meteorites.
Meteors often occur in 'showers' which can be related to the Earth moving through debris trails left by comets or asteroids (most likely 'extinct' comets).
Useful background information about meteors:
Meteor showers on Wikipedia:
IAU Meteor Data Centre:

International Meteor Organisation (IMO) - created in response to need for international cooperation in amateur meteor work:

Meteor visual observation form - submit your obs to the IMO:
observation form

Fireball observation form - submit your obs to the IMO:

American Meteor Society:
Meteor shower calendar, 2011:
Some Yahoo groups (membership required):
Astronomical Society of Victoria Meteor Section:
Eastern Australia Meteor Network:
More images:
 Meteor in Crux, 7 Feb 2011
Short, bright meteor in Crux, 14:14, 28 December 2010 UT
Canon 400D, 2 min at 105mm
Click on images to enlarge...
 Short streak as a tiny fragment of Halley's Comet burns up in the atmosphere - an Eta Aquarid meteor, 5 May 2011.
Southern Taurid meteor imaged from Norfolk Island, South Pacific, 15 November 2010.  Canon 400D on tripod, 18mm.
Geminid meteors from the 2009 shower
Canon 400D, 18mm, ISO 1600, F/4, 20-sec exposures
All images taken from Bright, Victoria, Australia, unless otherwise indicated.
36.7S, 147.0E