5e Combat
5e Combat has lots of steps and actions. The details are available on official pages and just kept her for more fast-loaded reference and includes some interpretations and house rules.
https://roll20.net/compendium/dnd5e/Rules:Combat
https://www.dndbeyond.com/sources/basic-rules/combat
The Order of Combat
A typical combat encounter is a clash between two sides, a flurry of weapon swings, feints, parries, footwork, and spellcasting. The game organizes the chaos of combat into a cycle of rounds and turns. A round represents about 6 seconds in the game world. During a round, each participant in a battle takes a turn. The order of turns is determined at the beginning of a combat encounter, when everyone rolls initiative. Once everyone has taken a turn, the fight continues to the next round if neither side has defeated the other.
Combat Step by Step
- Determine surprise. The GM determines whether anyone involved in the combat encounter is surprised.
- Establish positions: The GM decides where all the characters and monsters are located. Given the adventurers' marching order or their stated positions in the room or other location, the GM figures out where the adversaries are how far away and in what direction.
- Roll initiative: Everyone involved in the combat encounter rolls initiative, determining the order of combatants' turns.
- Take turns. Each participant in the battle takes a turn in initiative order.
- Begin the next round. When everyone involved in the combat has had a turn, the round ends. Repeat step 4 until the fighting stops.
Surprise
A band of adventurers sneaks up on a bandit camp, springing from the trees to attack them. A Gelatinous Cube glides down a dungeon passage, unnoticed by the adventurers until the cube engulfs one of them. In these situations, one side of the battle gains surprise over the other.
The GM determines who might be surprised. If neither side tries to be stealthy, they automatically notice each other. Otherwise, the GM compares the Dexterity (Stealth) checks of anyone hiding with the passive Wisdom (Perception) score of each creature on the opposing side. Any character or monster that doesn’t notice a threat is surprised at the start of the encounter.
If you’re surprised, you can’t move or take an action on your first turn of the combat, and you can’t take a reaction until that turn ends. A member of a group can be surprised even if the other members aren’t.