Orogeny refers to forces and events leading to a large structural deformation of the Earth's crust and uppermost mantle caused by the interaction between tectonic plates. Orogens or orogenic belts develop when a continental plate is crumpled and pushes upwards to form mountain ranges. These involve a great range of geological processes collectively called orogenesis.

The word "orogeny" comes from the Greek (ὄρος oros for "mountain" and γένεσις genesis for "creation" or "origin"). Orogeny is the primary mechanism by which mountains are built on continents.

Formation of an orogen is accomplished in part by the tectonic processes of subduction (where a continent rides forcefully over an oceanic plate (noncollisional orogens) or convergence of two or more continents (collisional orogens).

More Info: en.wikipedia.org