Events — reacting to the world

So far your scripts run top to bottom and finish. But games aren't linear — a player can touch a coin any time, or never. How do you write code that waits patiently and springs into action only when the moment comes? You don't wait. You listen. That's events.

#The idea: Roblox calls you back

An event is a signal an object fires when something happens. When you write:

part.Touched:Connect(function(hit)
    print("Something touched the part!")
end)

You're not running anything yet. You're telling Roblox: "whenever part gets touched, call this function." The function is a callback — code that isn't run by you, but by the engine, at exactly the right moment.

This is the single most useful pattern in Roblox. Most of your game will be event callbacks.

#.Touched — the first event

The .Touched event fires whenever any other part touches the part. It passes one argument to your function: the thing that touched it.

local coin = workspace.Coin

coin.Touched:Connect(function(hit)
    print("Touched by " .. hit.Name)
end)

Note the function is anonymous — no name, created in place, and passed straight to :Connect. The engine will call it with hit filled in whenever the event fires.

#ClickDetector — for clickable parts

A ClickDetector is a child object that makes a part clickable. The .MouseClick event fires when a player clicks it.

local button = workspace.MysteryBox

button.ClickDetector.MouseClick:Connect(function(player)
    print(player.Name .. " clicked the box!")
end)

MouseClick gives you the player who clicked — exactly who you need for player-specific rewards.

#Other events you'll meet soon

Events are everywhere in Roblox:

They're all connected the same way: thing.EventName:Connect(function(...) end).

local coin = workspace.Coin
-- your connect here

#Common mistakes

• Writing :Connect() when you meant to call the function. coin.Touched:Connect(myFunction()) calls myFunction immediately and connects its return value — usually nil, so nothing ever runs. Pass the function without parentheses: :Connect(myFunction).
• Forgetting the ClickDetector. A part isn't clickable until it has one. No detector, no MouseClick.
• Expecting the callback to run at Connect time. Nothing happens when you write the code. It waits for the event.
• Connecting inside a loop. Connect inside while true stacks a new callback every tick, and the event fires all of them at once. Connect once, at the top of your script.

That's the whole Luau basics box: scripts, variables, types, numbers, strings, booleans, functions, conditionals, loops, tables, timing, and events. Next section: data — how a player's progress is stored and trusted.