Induction heating (IH) is a particular process which uses electromagnetic fields for heating conductive materials (steel,copper,brass,aluminium...).
The main principle of IH is described in the following figure where a coil (inductor) is wound round a cylindrical conductive work-piece.

In the  exciting coil, an a.c. current I1 of suitable frequency flows and creates an alternating magnetic flux F; the flux F, linked with any ideal conducting path in the work-piece to be heated, induces a.c. currents Ik; the induced currents Ik heat the work-piece by Joule effect.
The main difference from a traditional heating process is the location of heat sources which are distributed inside the work-piece.  For this reason the IH process is very fast and controllable. Depending on the frequency used the heating can be superficial (induction surfacehardening) or deep in the piece (forging, heat treatment etc.).
The main advantages of this technology are: high production rate due to the high specific power delivered to the work-piece, high automation of the process, precise repeatability of treated pieces, in-line installation, low floor space needed,  controllability of temperature with high precision, avoiding of deformation of pieces especially in surface hardening, primary energy saving, reduction of CO2 emissions, safe and clean work ambient for employees.
There are a lot of applications where IH is used in different industries: melting of metals, heat treatments (hardening, tempering, annealing) , forging, hot rolling, surface hardening, cold crucible melting, welding, pre-heating, dry-coating, special applications. All these applications get benefits from the suitable characteristics of this technology.