many people rush to buy house now, why?

many people rush to buy house now, one house always have a few offer, push price high , some house was pending then back to market again after one month, because the buyer did not get loan from bank, the bank think that buyer is over pay, some house pay full list price or 120% , the ohio house market is very hot now, like 2002-2006. people competition each other and offer high price, I do not undersand why? any one can explani?