Every metal oxide semiconductor field effect transistor or MOSFET has the same set of basic components: gate stack, channel region, source and drain. The source and drain are chemically doped so that they are either rich in mobile electrons (n-type) or devoid of them (p-type). The channel region has opposite doping to the source and drain.
In the planar versions of transistors used in advanced microprocessors prior to 2011, the gate stack of the MOSFET was located directly above the channel region and was designed to project an electric field into the channel region. Applying a sufficiently large voltage to the gate (relative to the source) creates a layer of mobile charge carriers in the channel region, allowing current to flow between the source and drain.