sleep

Suspends the current thread for duration seconds (which may be any number, including a Float with fractional seconds). Returns the actual number of seconds slept (rounded), which may be less than that asked for if another thread calls Thread#run. Called without an argument, sleep() will sleep forever.

Time.new    #=> 2008-03-08 19:56:19 +0900
sleep 1.2   #=> 1
Time.new    #=> 2008-03-08 19:56:20 +0900
sleep 1.9   #=> 2
Time.new    #=> 2008-03-08 19:56:22 +0900