LiPo INFORMATION:
The letters S and P, when talking about a LiPo, refer to the cell orientation. For example if you have a 2s2p pack, that means that there are four cells in total, with 2 arranged in series (S) and 2 arranged paralell (P) to that series. If you take 2 cells and attach them in series, the voltage doubles. However, if 2 cells are connected in a paralell orientation, the capacity doubles, and voltage isn't affected at all. So running a 2S and a 2P allows you to double the capacity without raising the voltage and vice-versa. The "C" rating of cells corresponds to the pack's discharge current, in Amps, divided by the capacity of the pack. For instance, 72A/4.8A=15C. The higher the C rating, the higher the peak or continuous current draw possible.
Courtesy of XTreme RC issue 144