how to know if a key is being hold down?

i wanna know how to detect if a key is being held down, like if the player is holding down the W key. Thanks

Two events: InputBegan, and InputEnded. You can use these methods to detect when a key has been pressed and when a key has been lifted. I recommend storing these objects in a table so you can detect whenever ANY key is being held or is being lifted:

local UIS = game:GetService('UserInputService');
local pressedKeys = {};
UIS.InputBegan:Connect(function(Key, Processed)
	if (Processed) then return nil end;
	pressedKeys[Key.KeyCode.Name] = true;
end)

UIS.InputEnded:Connect(function(Key)
	pressedKeys[Key.KeyCode.Name] = nil;
end);

With this, you can check if the key is currently being held by doing:

while pressedKeys["W"] do
	wait();
	print("W is being pressed.");
end
print("W is not being pressed anymore.");