Stablecoins can be collateralized or non-collateralized. Collateralized stablecoins include fiat-backed, asset-backed, and crypto-backed stablecoins. They maintain stability by backing the value of the stablecoin with real-world assets. Non-collateralized stablecoins, such as algorithmic stablecoins, use algorithms to maintain stability without direct asset backing. The choice of stability mechanism depends on factors like liquidity, decentralization, audits, and complexity.