KCL $\frac{Junction}{Current Rule}$: The algebraic sum of currents at any junction is zero. Currents entering are positive; leaving are negative. Based on conservation of charge. Example: if I1, I2 enter and I3 leaves, then I1 + I2 = I3.

KVL $\frac{Loop}{Voltage Rule}$: The algebraic sum of potential differences around any closed loop is zero. Based on conservation of energy. Conventions: (a) Crossing a battery from - to + is a rise (+emf). (b) Crossing a resistor in the current direction is a drop (-IR). Choose current directions and loop directions, then apply systematically.

Strategy: For a circuit with n unknowns, you need n independent equations. Use KCL at (j-1) junctions (j = total junctions) and KVL for remaining equations from independent loops.