No-Limit Texas Hold'em Poker Competition Rules (Part 3): Order of Action
After reading this article, you will understand how players take turns in poker games, and what the differences are between pre-flop and post-flop action orders.
Action order: First round (before the cards are flipped)
In Texas Hold'em, each hand consists of four rounds of action from beginning to end. Basically, the players take turns acting clockwise, except that the player who acts first in the first round differs from those in later rounds.
Before the flop:
The first action round, in Texas Hold'em, is called...Pre-flopAt this point, the small blind (SB) and big blind (BB) will put in their chips first, and then each player will be dealt two hole cards. After seeing the hole cards, the player after the big blind, the UTG, must act first, and then the turn proceeds clockwise to the big blind player. (Each position in poker has a fixed name; new players can refer to...)This article(Introduction and significance of the name)

Action order: Rounds 2-4 (after the cards are flipped)
Flop, turn, and river:
After the pre-flop actions are completed, three community cards are dealt, and the second round of action begins, called the flop. From this point onward, the order of action changes to the small blind player acting first, followed by the players in clockwise order.
After the flop, the game proceeds to the turn, where the fourth community card is dealt. Actions then proceed clockwise, starting with the small blind. Finally, the game continues to the river, where the fifth community card is dealt. Players then see their cards and take their final turn.