Combination of Resistances in Series
When two or more resistances are connected end to end so that same current flows through each resistor they are said to be connected in series. So, when some resistances are joined in series, the total resistance of given series of resistances is equal to the sum total of individual resistances.
Combination of Resistances in Parallel
When two or more resistances are connected across a common point so that same current flows through different paths they are said to be connected in parallel.