Igneous rock is formed when magma cools down. The igneous rock is then pushed into the Earth which is the process of tectonic activity. Some, but not all of the igneous rocks will be pushed into the mantle of the Earth. The ones that are pushed to the mantle will be shown to great temperatures, which will cause them to melt and reform as magma. For the rocks that are not pushed into the mantle, they are broken down into sediment by weathering.
Sedimentary rocks are when the layers of sediment are compacted and then transformed into sedimentary rocks.