An Altcoin Season is a period where the price growth in the altcoin markets shadows that of Bitcoin. The Altcoin Season generally comes after a Bitcoin Halving event and lasts about 1 to 1.5 years.
This season is also marked by an increased growth in the users buying different altcoins as per their choice. The arrival of this altcoin season is typically characterized by a decreasing market dominance of Bitcoin and an increased market dominance of the rest of the altcoins.
To gauge this change in market dominance better, we use an altcoin indicator also known as an alt-season index.