Type of videogame console that has games and controller built-in, that is then connected to a TV. The controller parts get pretty wild. They're cheap!
You can categorise them as a few different types:
Pre-cartridge game consoles. Some are dedicated to one game, some contain multiple.
Famiclones or other SOC consoles, often in a rip-off controller shell. Usually have heaps of games, generally NES games including hacks, and sometimes a few original ones.
Licenced ones. Will usually have about five original games, often takes on classic arcade games. Have the best shell designs.
Fancy mini-consoles by Nintendo, Sega, Sony, Neo-Geo, Taito etc., based on old hardware running games via emulation.