What is an s trap?

S traps can be installed if you are replacing an existing s trap, other than that I believe they are no longer allowed by code. If you look under most sinks you will see a P trap, frequently called a J trap. It drops down from the verticle drain pipe and forms a J shape before going horizontally into the wall. A S trap is like 2 Js put togethermaking an S shape laying on its side so it can drain straight down through the floor. They are prone to siphoning so not allowed.