Altcoins are cryptocurrencies that serve as alternatives to Bitcoin, encompassing a wide range of digital assets with varying functions, technologies, and market capitalizations. They include well-known coins like Ethereum, Litecoin, and Ripple, as well as thousands of smaller projects. Altcoins often aim to improve upon Bitcoin’s limitations or introduce new features, such as smart contracts or enhanced privacy. Investors track altcoin trends for diversification and potential growth opportunities in the broader crypto market.