What is a Hotend?
A hotend is a device that heats and melts filament for 3D printing. It consists of a heating element, a thermistor to regulate temperature, and a nozzle through which the melted filament is extruded. The hotend is a crucial component of a 3D printer, as it allows the printer to build objects layer by layer.
But in simple terms, It is called a "hotend" because it gets very hot in order to melt the plastic but for some reason.. nobody ever talks about the "coldend" go figure.