"Alt season" in the world of crypto is a period when the prices of altcoins (all coins other than Bitcoin, such as Ethereum, Solana, Cardano, etc.) rise much faster compared to Bitcoin.
In short:
Alt = altcoin
Season = a specific season or period
Characteristics of alt season:
Bitcoin usually has already risen first or is stabilizing.
Many altcoins rise by tens to hundreds of percent in a short time.
Many investors and traders start moving funds from Bitcoin to altcoins to seek greater profits.
Usually, alt season occurs after Bitcoin hits an all-time high or is in a consolidation phase. However, there is no definite benchmark, so it is still necessary to be cautious as the risks are also high.