1. The sum of reciprocals of the individual resistance is equal to the reciprocal of effective resistance.
2. The currents in various resistors are inversely proportional to the resistances (higher is the resistance lower is the current through it).However the total current is the sum of the currents flowing in the different branches.
3. The voltage across each resistor is same.
4. The effective resistance of the combination is less than the individual resistance in the combination.
5. This combination is used to decrease resistance in the circuit.