Thermoforming is a shaping process that consists of placing a piece of glass on a support (usually around its perimeter) in an initially cold oven and heating it until the glass piece becomes viscous. Around 700°, under the action of gravity, the plate deforms and stretches until the desired precise effect is obtained. The piece can also be shaped by blowing, suction or any other mechanical action.
>Link to the definition of the IDverre website