<Li> National Engineers Week (U.S.) </Li> <P> Monday after Sunday of Forgiveness (Eastern Christianity): February 19 </P> <Ul> <Li> Great Lent begins <Ul> <Li> Clean Monday </Li> </Ul> </Li> </Ul> <Li> Great Lent begins <Ul> <Li> Clean Monday </Li> </Ul> </Li>

Why only 28 or 29 days in february