Volatility Measurement also known as the ATR.

Used by traders to measure the degree of price volatility.  It is generally measured using Daily Candlesticks

The true range is the largest of the:

Most recent periods high – low

Absolute value of the most recent period’s high – previous close

Absolute value of the most recent periods low – the previous close

Many diverse uses by traders:

To determine entry points

To determine stop losses