Commands stuff

Hi, AbleDuckMc here.
I realised many people want to make an adventure map but don't know that much about commands
So I'm gonna try to explain EVERYTHING y'all ask about in the comments

Imma start of with one so ya'll know
/execute
execute is a command that lets you..well.. execute commands at specific areas/mobs/players for example if you want the command /say hi to execute when a player stands on red concrete you type /execute at @a if block ~ ~-2 ~ red_concrete run say hi thats a simple thing but for example you can also do /execute at @a run summon tnt ~ ~10 ~ This summons a lit tnt ten blocks above every player you can use these examples for other stuff like changing the blocks or putting names instead of @a
also something REALLY important for beginners is what all the @ does
@a all players in the world/server
@e all entities/mobs/players in a world/server
@r a random player OR by typing @r[​type=!player] this makes it so that a random entity does whatever u put in the command
@s yourself
@p nearest player

Comment what tutorial I should give next I'm happy to help!!