What is the difference between Bitcoin and altcoins?

Bitcoin is the first and largest cryptocurrency by market value, created in 2009. It operates on a proof-of-work system where miners validate transactions. Altcoins are all other cryptocurrencies besides Bitcoin, including Ethereum, Ripple, and thousands of others. Altcoins often serve different purposes: Ethereum enables smart contracts, while others focus on privacy, speed, or specific use cases. Bitcoin dominates the market with the highest security and longest track record, making it less volatile than most altcoins. Altcoins typically have smaller market caps, higher price volatility, and varying levels of adoption. Bitcoin is often considered digital gold, while altcoins are viewed as riskier investments with higher growth potential but greater downside risk.