A long electrical cord with a Electric Plug at one end and at least one self-containing Electrical Outlet (usually two or three) in the other. Its length is usually long, enabling the connection of appliances far from the nearest wall socket as well as the connection of multiple electrical objects when there are not many wall sockets to accommodate them all.
A Power Strip is basically the same thing, but with either one switch overall to regulate the flow of electricity to all of the sockets or one switch per socket to control and isolate each socket. The switch(es) also helps prevent electrical surges that damage the connected appliances.