It uses transparent boxes to give the impression of a heat map. Due to limitations of my own skill and possibly pinescript it is not possible to render it in a useful manner using different colors that depicts buy and sell interests respectively. This means it works more like a volume profile in that it mixes the buy and sell interest together in the heat map. This can still be helpful because it help traders focus their attention on areas other than the current price candle.
In my limited time of using it, it seems like on the large timeframes the highlighted areas is where the price wants to go, and on small time frames the darkest areas is where the price wants to go. But i will leave it up to any user to spot and use their own patterns with the indicator.
Last but not least, the indicator only uses the last 50 candles, which can be too little on a small timeframe. Unfortunately the way i have done it this limitation is hardcoded in the script due to how pinescript works, by editing the code you can increase it. (Put max_boxes_count = x after overlay = true. Maximum number is 500)
Hope you enjoy. Have a nice day.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.