"Altcoin" is a portmanteau of "alternative coin" — any cryptocurrency that is not Bitcoin. Ethereum, Solana, XRP, Cardano, Dogecoin, and thousands of others are all altcoins. While Bitcoin is the dominant cryptocurrency by market capitalization and brand recognition, altcoins have historically produced both the largest gains and the largest losses in the crypto market.
Altcoins were created for various reasons: some aim to improve on Bitcoin's limitations (faster transactions, smart contract capability, privacy features), some serve specific use cases (decentralized finance, NFT platforms, oracle networks), and some are explicitly speculative. The quality and legitimacy of altcoins varies enormously — from well-established projects with billions in daily volume to tokens with no real utility.
Altcoin season (often called "altseason") refers to a period when the majority of altcoins significantly outperform Bitcoin. Rather than the entire crypto market rising together, altseason is characterized by capital flowing specifically from Bitcoin into smaller cryptocurrencies in search of larger percentage gains. During peak altseason periods in 2017 and 2021, many altcoins appreciated 10x, 50x, or even 100x while Bitcoin's gains were more modest.
Altseason historically follows a recognizable pattern:
A significant Bitcoin price increase draws new capital into the crypto market from outside. Early adopters and institutional money typically enters through Bitcoin first — it is the most liquid, most regulated, and most widely understood entry point.
Once Bitcoin's rate of appreciation slows, money flows into Ethereum, which benefits from its role as the primary smart contract platform and gateway to DeFi and NFT ecosystems. Ethereum often outperforms Bitcoin at this stage.
Capital continues flowing further out the risk curve into mid-cap altcoins — established projects with real utility but smaller market caps. These typically see 3–10x gains during this phase.
At peak euphoria, capital reaches the smallest and most speculative tokens. This phase is typically short-lived and marks the highest risk moment in the cycle.
The same properties that enable altcoin outperformance also create extreme risk. During bear markets, altcoins historically lose 80–95% of their value measured in both US dollars and Bitcoin. Many never recover to their previous highs. The vast majority of altcoins that existed in 2017 are now effectively worthless. Liquidity in smaller altcoins can evaporate rapidly in a downturn, making it difficult to exit positions.
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