Five cards, one exchange, nothing on show until the end.
The oldest form still played, and the one with the least information. Nothing is ever face up.
Everyone is dealt five cards face down, and there is a betting round.
Starting to the dealer's left, each player still in may discard any number of cards and be dealt that many replacements. Keeping all five is called standing pat. A second betting round follows.
Remaining players reveal their hands and the best five-card hand takes the pot.
With no exposed cards, how many cards someone drew is nearly all you have to go on. Drawing three usually means a pair, drawing one means two pair or a four-card straight or flush, and drawing none means either a made hand or a bluff worth paying attention to.