What is this indicator?
Price levels that have caused price to stall or reverse multiple times in the past, making a repeat reaction there likely. The more a level has been tested, the higher both its credibility and its eventual chance of breaking become.
How to read the chart
Price approaching these levels sets up probable reactions (support, resistance, or a breakout), and traders usually watch how price behaves in exactly these zones.
Practical tip
These levels aren't definitive — they're just probable reaction zones; getting confirmation from price action or volume before deciding is recommended.