The Altcoin Season Index measures whether altcoins (cryptocurrencies other than Bitcoin) are outperforming Bitcoin over a 90-day window. The index ranges from 0 to 100: below 25 is "Bitcoin Season" (BTC leading), 25–75 is mixed or neutral, and above 75 is "Altcoin Season" (altcoins leading). It helps investors see when capital is rotating into or out of Bitcoin versus the rest of the market. That's useful for timing diversification into alts or into BTC.
Historical values and range high/low show how the Altcoin Season Index has moved over the selected period. Comparing yesterday, last week, and last month with the range extremes helps you see whether the market is near a seasonal extreme (e.g. strong Bitcoin or Altcoin season) or shifting between regimes.