/gamemode

Syntax

/gamemode <gamemode> [<target>]

Argument	Kind of value	What to type
<gamemode>	Game mode	The game mode: survival, creative, adventure or spectator.
<target>	Target selector	The players whose game mode is changed. Defaults to yourself. One or more players.

Permission level	2: operators, worlds with cheats on, command blocks and functions
Works in	Operators on multiplayer servers, singleplayer worlds with cheats enabled, and command blocks and functions.
Result	Reports "Set own game mode to ..." or "Set <player>'s game mode to ...". The number /execute store saves is the number of players whose game mode changed.
No target	Without a target the command changes your own game mode. It then has to be run by a player, so a command block or the server console must name a target.
Already in that mode	Players who are already in the chosen game mode are skipped without a message and are not counted.
Message to the player	A player whose game mode is changed by someone else is told about it, unless the game rule send_command_feedback is off.

/gamemode creative

Puts you in Creative mode.

/gamemode survival

Puts you in Survival mode.

/gamemode spectator @s

Puts you in Spectator mode.

/gamemode adventure @a

Puts every player in Adventure mode.

/gamemode survival @p

Puts the nearest player in Survival mode.