A-2-3-4-5 is considered a five-high straight, and it is called a wheel or bicycle; this is the only time an ace plays as a low card. An ace-high straight flush is called a royal flush and it cannot be beaten. The only time it ties is when all 5 cards to the royal flush, i.e. A&e K&e Q&e J&e 10&e, are on the community board.
