Floods are conditions when there is overflow of water in areas. in india,places that are prone to floods are assam, bihar, odisha, etc. in floods people face a lot of problems. they fall sick,there is shortage of food etc. some floods even lasts for days. 
Rain water falls a big mountains as well as upon plains. as  the river bed in lower in level, all the rain water flows to low land and rivers. when rainfall is heavy, river, streams and another channels cannot contains all the river water in their beds. then the water overflows their banks this is called floods.