An electrical outlet is an opening or series of openings connected to a wired power source meant to power electrical equipment and components. The electrical outlet is one of the most commonly used items in a home or building. They are nearly universally used, but many countries may have different standards or voltages. Therefore, not all electrical outlets, or the components they are intended for, are compatible with each other.

An electrical outlet provides power to an electronic component by using a wire to take power to the outlet. The plug of the component then transfers power to the device requiring it. Another wire then takes the electricity back to its original location. For simplification, in a home environment, this is the electrical panel. Due to this round-trip routing, it is often called an electrical circuit.

In the United States, the standard electrical outlet has a pair of parallel vertical slits less than an inch (2.5 cm) apart, plus a round opening centered below the vertical slits. The round opening is for the ground, which offers some safety. The voltage in the United States is usually 120. In addition to the United States, this standard plug is often used in the eastern portions of South America, some Caribbean countries and in some Middle Eastern countries.

In most of Europe, the standard electrical outlet has two openings spaced horizontally less than an inch (2.5 cm) apart. Its voltage is usually 220 to 230, but it can vary by location. This type of plug is most commonly known as the Europlug, because of its use in that portion of the world. It is also the most widely used electrical outlet type internationally.

In the United Kingdom, the main electrical outlet plug has two horizontal slits at the bottom, and one vertical slit slightly above those horizontal ones. The slits together form a triangular shape. The plug can also be found in other portions of the world, such as Latin America and Africa. Its most common voltage is 230.

For travelers, international adapters can help make devices you have compatible to be plugged into outlets of other countries. However, just because you may be able to plug an electronic component into an international outlet does not mean you should. If the component is not made for higher voltage, you will also need a converter to lessen the voltage. Otherwise, the electricity will overpower the equipment and cause it to become inoperable.