/execute executes another command but allows changing the executor, changing the position and angle it is executed at, adding preconditions, and storing its result. There are fourteen[JE only] / eleven[BE only] instructions (aka. subcommands) for the /execute command. Multiple subcommands can be chained after /execute. Subcommands are divided into 4[JE only] / 3[BE only] categories ... More @Wikipedia
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