Kirchhoff's Voltage and Current Laws

Kirchhoff's Current Law

Kirchhoff’s current law is similarly simple:
the sum of the currents flowing into any point or node of a circuit is zero.
So, in the case of the circuit node shown here:

I1+I2-I3-I4=0

Again, it is not the direction in which the currents are defined as flowing that is important (if they turn out to be flowing in the opposite direction then the value of the current in the defined direction will be negative) it is that they must be treated consistently.

The law is also common sense: current is moving charge – if the charge flowing into any node in the circuit is not balanced by the same amount of charge leaving the node then this would imply that charge was accumulating at the node.