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Igneous rocks are one of the three main groups of rocks that make up the Earth's surface. True to their the Latin root ign- of their name, they are "fire" rocks.  They form mostly from molten material, which includs ejected lava, ash and blocks blown from volcanoes and other such material. Igneous rocks also formed by the cooling of molten magma beneath the Earth's surface.
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Many igneous rocks are easily distinguishable from sedimentary and metamorphic rocks through differences in their structure, texture - the way the mineral grains fit together, and relationships to other rocks around them.
Many geologists ans scientists believe that at a point in history the entire Earth was made of such material, which has been gradually cooling over billions of years of geologic time and all rocks have originated from igneous sources.
Pictures: Above- An igneous rock feild
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