Electric current consists of charge particles - usually electrons - moving through a conductor. Between collections of positive and negative charges there exists a potential difference called 'voltage'. If a conducting path exists between two charged groups, charges will flow from one to the other, constituting an electric current, and usually consists of a flow of electrons from the more negatively charged body to the more positively charged one. Metals and other materials that allow the flow of electric charge through them are known as conductors. Materials that resist the passage of an electric current are known as insulators.

A direct current (DC) is a constant flow between two points having a different electrical potential and the charge flow is one way, as from a battery. Or it may be alternating current (AC), as from a mains supply. Here, the charge flows alternately backwards then forwards in a circuit many times every second. By convention, a positive current is defined as that which flows from a higher potential to a lesser one, driven by the potential difference.

An electrical circuit is a network that has a closed loop, giving a return path for the current. A network is a connection of two or more simple circuit elements, and may not necessarily be a circuit.

You need 2 different metals, e.g. copper & steel, or a penny and a nail. Stick them carefully into a citric fruit such as a lemon (not your hand!). Attach a wire to each piece of metal (crocodile clips work best) and place the other ends onto your tongue. You should feel a tingle from the electricity.

The current isn't enough to power a small light bulb, but you could try putting more metal pairs into the same, or other, pieces of citric fruit, and connecting the wires in parallel.