A circuit is a closed path or loop around which an electric current flows.
without a circuit you can't make an elctric current.
There are many types of circuits
open, close, series and parallel
Open circuits
an open circuit have not a complete path that means that is not functional because if you put a cable to atach a bulb and a ba b is gonna get energy from the battery but is not going to get his energy back so te bulb culd not ligth up again.
Closed circuit
A closed circuit has a complete path for current to flow.
series circuits
In a series circuit, the same current flows through all the components.
Parallel circuits
Parallel circuits are like the smaller blood vessels that branch off from an artery and then connect to a
vein to return blood to the heart. Now think of two wires, each representing an artery and a vein, with
some smaller wires connected between them. These smaller wires will have the same voltage applied to
them, but different amounts of current flowing through them depending on the resistance of the
individual wires.