Recessed
Recessing is the easiest and most commonly used method of installing a cooktop.
To lower your cooktop, make a hole in the countertop following the instructions that come with the cooktop. It then often needs to be secured with brackets, screws or springs, following the instructions. The hob rests on top of the worktop around the hole when folded down.
Planning
Instead of recessing the cooktop into the countertop, you can plan it. A hole is still made in the countertop, but the cooktop is mounted so that it is completely level with the table. Professional help is needed to level your cooktop, and it requires a cooktop with a straight edge.