What's being averaged
The 200-week moving average takes weekly closing prices over the trailing 200 weeks (roughly 3.8 years) and averages them, producing a slow-moving trend line. Because 200 weeks is close to the length of one halving cycle, the line effectively smooths out an entire boom-and-bust cycle at a time, which is part of why it gets treated as a long-term reference, never as a short-term trading tool.
The "never broken" track record
Across Bitcoin's trading history, weekly closing price has dipped below its own 200-week moving average only during the deepest points of major bear markets — briefly in 2015, briefly in 2018, and briefly during the March 2020 pandemic crash. Each occasion was short-lived, with price recovering back above the line within weeks to a few months. That track record covers three or four discrete episodes across roughly 15 years of price history.
Reading the heatmap framing
This site displays the ratio of current price to the 200-week average as a heatmap-style gauge, coloring how stretched price is above (or how compressed it is below) its own long-run trend. This is purely a price-derived metric — it carries no on-chain cost-basis information the way MVRV or realized price does, which is why this site places it in the statistical tier, not the on-chain one.