...are the new kids on the block as regards catering equipment. Despite having been invented more than half a century ago, high manufacturing costs have kept these devices off the market until recent times. Small single pot units are now available at fairly modest prices, although that does depend on your definition of 'modest'. We offer big discounts off shop prices, but larger versions still command quite a premium over standard gas and electric hobs.
An electric coil produces a magnetic field under the glass surface. If a ferrous metal cooking container is brought into close proximity of the glass, an electrical current is induced, and, if its resistance is sufficient, the metal will heat up, cooking the food within. You will have noticed the 'ifs' in that statement: induction hobs only work with suitable cookware.
Induction cooking has its advantages. Less heat is wasted, creating a cooler and safer cooking environment. Heat is instantly controllable, and shuts off when the pan is removed. Less heat wastage means greater efficiency (some manufacturers make comparisons with gas cooking, however it should be noted that gas is a cheaper energy source. A US study judged induction hobs to be 12% more efficient than those using standard electric elements).
Disadvantages include the high purchase price of these complex units, and the need for specialist cookware. There is also the possibility of prohibitive future repair costs in the event of malfunction. The ceramic glass surface is tough, but can be damaged if your kitchen staff are destructive enough.