brushless conversion questions

[rcsammy]

ok then :)
well i went onto maxamps.com and was looking around
and i saw that alot of the batterys are 2S2P or 4S2P.... and im a bit confused with the 2P part, so could anyone explain that please?

i was looking at other peopls conversions and was amazed at the runtimes people were geting 30-45 minutes on one pack is brilliant, if i could run 3x 5minute qualifiers and then a 15minute final(30 minutes in total) with just one battery then i could afford to spend more on one good battery rather than two not so good ones