An electrical circuit is a loop which provides a path for electric current (electric charge) to flow. This loop must be closed. In other words, the current must be able to flow from positive to negative terminals otherwise the flow will not take place. The charge is made possible by a source such as a battery which motivates the electrons to move in the conductor. So it is the movement, in other words the flow of these electrons that constitutes the electrical charge. Note that this happens from negative to positive terminal which is the opposite of accepted convention for current direction. In this closed loop we mentioned above, there are components we want, to make our electronic devices possible, such as motors, resistors, inductors capacitors, light bulbs, logic gates and so on.
The loop must be made of conductors. This conductor is most commonly conductive metal wire but other mediums such as conductive polymers or liquids, are also possible. Current can also be carried by electromagnetic induction, which requires no physical medium. Examples include transformers, radio frequency signals.
