Meteoroids are small heavenly bodies which revolve around the sun. Those meteoroids which reach the surface of the earth without getting completely deteriorated are called meteorites. When the meteoroids enter the earth’s atmosphere, due to immense pressure they get converted to fire balls called meteors. They are also known as shooting stars and appear as a streak of light in the sky. With reference to the composition of the meteorites they a broadly classified into three types: stony meteorite, iron meteorite and stony iron meteorite. Stony meteorites are usually made of silicon. Chondrites and Achondrites are some of the most common stony meteorites. Iron meteorites are mainly composed of iron with nickel in small proportion. Stony iron meteorites are made up of both silica and iron. The motion of the meteorites is influenced by the earth’s gravitational effect. A very dense collection of meteors are formed by the deterioration of the comets. When the earth’s orbit crosses this meteor stream, large number of meteors enters the earth’s surface resulting in meteor rain. The meteorites are often recovered and preserved for research on their origin.A meteorites known as ALH84001, is believed to show evidence of life on mars.