Which part is directly responsible for melting and extruding the filament in a 3D printer?

The extruder is the component in a 3D printer that is directly responsible for melting the filament and then pushing it through the nozzle to create the desired shapes during the printing process. It works by feeding the thermoplastic filament into a heated chamber where it is melted, enabling it to be shaped as it is deposited layer by layer onto the print bed.

The print bed serves as the surface where the object is being built but does not play a role in the melting or extrusion of the filament. The printhead, on the other hand, houses the extruder and nozzle but does not perform the melting process itself; it is the extruder that does that. Ribbon is not a standard component in 3D printing technology and does not relate to the process of melting or extruding filament.