Average true range (ATR) stands for Average True Range which measures how much price moves on average. It has to be used as a volatility indicator that shows how much an asset moves, on average, during a given time frame.
Understanding volatility is important to make the right trading decisions as we will see later. Understanding how volatility changes with market context can help you make much better trading decisions as well.
I like to use this one for margin trading and on lower tf (1h, 2h, 4h).