An altcoin refers to any cryptocurrency other than Bitcoin. The term is a blend of "alternative" and "coin," representing the variety of cryptocurrencies that emerged as alternatives to Bitcoin. While Bitcoin was the first cryptocurrency and remains the most well-known and valuable, thousands of altcoins have been developed since its launch in 2009.

Types of Altcoins:

1. Stablecoins: Cryptocurrencies pegged to stable assets like fiat currencies (e.g., USD) to reduce price volatility. Examples: Tether (USDT), USD Coin (USDC).

2. Utility Tokens: Tokens used to access specific services or products within a platform. Examples: Chainlink (LINK), Filecoin (FIL).

3. Governance Tokens: Allow holders to vote on changes to a blockchain protocol. Example: Uniswap (UNI).

4. Security Tokens: Digital tokens that represent ownership in assets like stocks or real estate.

5. Meme Coins: Often created as jokes or based on internet memes but can gain popularity. Examples: Dogecoin (DOGE), Shiba Inu (SHIB).