A receptacle is an electrical device, also referred to as an electrical outlet, where a plug can be inserted. A typical receptacle has two vertical slots. The shorter vertical slot should be where the hot wire is connected (usually black) and the larger slot is where the neutral wire is connected (usually white). At the bottom of the receptacle will be a hole for the ground prong which is usually connected to the ground wire (usually the bare copper wire or green wire). This is your average 120-volt receptacle, but there are different types of receptacles. Receptacles have changed over time to comply with standards. There was a time when receptacles didn't have a hole for the ground prong. Different countries can have different receptacles because of competing standards. Also, there are different types of receptacles available for 240-volt circuits compared to 120-volt circuits.