dt is the most common shorthand for delta-time, which is usually passed through love.update to represent the amount of time which has passed since it was last called. It is in seconds, but because of the speed of modern processors is usually smaller than 1 (values like 0.01 are common).
Increase a variable x by 1 every second
x = 0 function love.update(dt) x = x + dt end
Change a position x at a fixed speed while a key is held down
x = 0 speed = 32 function love.update(dt) if love.keyboard.isDown("right") then x = x + (speed * dt) -- x will increase by 32 for every second right is held down elseif love.keyboard.isDown("left") then x = x - (speed * dt) end end