Range

The measured sense first. The range of any interval is its highest price less its lowest price, which is why a single bar has a range, a session has a range, and so does a year. The true range is a variant that accounts for a gap: it takes the greatest of the interval's own high to low distance, the distance from the previous close up to the high, and the distance from the previous close down to the low, so a market that opened away from where it closed is not recorded as quiet. Averaging the true range over a window gives the average true range, which is the form most indicators use.

The descriptive sense names a condition rather than a number. A market is said to be in a range when successive highs stall around one area and successive lows hold around another, so the band contains the move instead of the move extending. Those two areas are resistance and support respectively, and the band's edges are drawn by eye from prior turning points, which means two readers place them slightly differently and neither is wrong.

The trip is comparison. A range is quoted in the instrument's own price units, so the same figure means something entirely different on an index and on a currency pair, and even within one instrument a range widens simply because the price level rose. Ranges are therefore normally compared as a proportion of price or against the instrument's own recent readings rather than against another market's. A range is also frame dependent in the same way a candle is: the daily range contains every intraday range inside it, and neither describes the other.