According to Coins.ph, an altcoin is any cryptocurrency other than Bitcoin, with prominent examples including Ethereum, XRP, and Solana (source: Coins.ph, May 20, 2025). Each altcoin features unique utilities and use cases in the Web3 ecosystem, making them popular choices for active traders seeking diversification and exposure to fast-moving crypto markets. Monitoring top altcoins is crucial for traders as these assets often experience higher volatility and trading opportunities compared to Bitcoin, especially during altcoin seasons.