Average True Range (ATR)
A technical analysis indicator developed by Welles Wilder. It is a 14-period Moving Average of the True Ranges.
The True Range is calculated as the greatest distance between: Current High to Current Low, Previous Close to Current High, and Previous Close to Current Low.
Average True Range measures volatility. Wilder perceived a high reading of the ATR as characteristic of bottoms after a sell-off. Similarly, low readings of ATR are characteristics of sideways movements either at tops or bottoms.