Rule 1. Because of the conservation of energy the sum of the voltages around a closed conducting loop (that is, a circuit) must be zero. In other words, since voltage and work are related, we are saying the net work done must be zero.

Kirchhoff's Current Law

Kirchhoff's law simply states that the amount of current entering a point has the be equal to the amount of current leaving a point (once again, charge is not consumed or created at a point). The other way of looking at Kirchhoff's law is when a circuit splits in to two directions that the current entering the junction (which we will call I total) is equal to the sum of the currents that split off.