Initiative

Initiative determines the order of turns during combat. Initiative is calculated by Dexterity modifier plus D20 plus any other relevant modifiers.

Sometimes a DM might have combatants use their Initiative scores instead of rolling Initiative. Your Initiative score equals 10 plus your Dexterity modifier. If you have Advantage on Initiative rolls, increase your Initiative score by 5. If you have Disadvantage on those rolls, decrease that score by 5.

Surprise. If a combatant is surprised by comabt starting, that combatant has Disadvantage on tehir Initiative roll. For example, if an ambusher starts comabt while hidden from a foe who is unawaare that combat is starting, that foe is surprised.