as above. The royal flush is a case of the straight flush. It can be formed 4 ways (one for each suit), giving it a probability of 0.000154% and odds of 649,739 : 1.

The Royal Flush is top on the list of poker hand rankings. This is the strongest possible hand in poker and can never be beaten. It is made when we have the Ace-high straight while holding cards all of the same suit.

Etiquette is the set of rules and manners that dictate behavior, both in personal and professional settings. Poker etiquette is the collection of norms and rules in and around the poker tables. If you don't know proper poker etiquette, you're bound to make obvious wrong moves and gaffes that can get you into trouble.