A meteor is what you see when you watch a meteor shower: a streak of light. The really bright ones are called bolides or fireballs.
A meteoroid is any object moving through space that is larger than a speck of dust but smaller than an asteroid. When a meteoroid enters Earth’s atmosphere, it is heated to luminosity; when we see it shooting across the sky, we call it a meteor. While watching the Perseid meteor shower one year, I wondered how big the Perseid meteoroids are. (I imagined them to be the size of apples or softballs.) The majority of meteoroids we see as meteors range from the size of a small pebble to the size of a grain of sand.
A meteorite is a meteoroid that was big or tough enough to survive the journey through the atmosphere and strike the surface of the Earth. Or the living room couch of Ann Hodges of Sylacauga, AL.