Expanding on "delay's" post.
Kirchoff's current law (KCL) states the sum of the currents entering a node must equal the sum of the currents leaving the node. This is an application of the principle of the conservation of charge.
Kirchoff's voltage law (KVL) says that the sum of the voltage rises (e.g., batteries) and drops (e.g., resistors) in any loop must equal zero. This is an application of Faraday's law.
Therefore, applying KVL the total voltages in a series circuit are additive while applying KCL the current is constant in any series loop.
Conversely, applying KCL the total current through (leaving) a parallel circuit is the sum of the individual currents and by applying KVL the voltage in a parallel set of components is equal (they form loops with each other -- and, instinctively, they are across the same point).