Which two processes result in the formation of igneous rocks?

I think the two processes are Melting and solidification. For example for the formation of igneous rocks from metamorphic rock, it must first melt. Once molten, it its liquid constituents cool and solidify, it has become an igneous rock. Metamorphic rock can become molten by exposure to heat and pressure from depth of burial and compression through tectonic plate subduction, or from close proximity to a magmatic heat source.