Stablecoins promise to bridge fiat currencies with the worldof cryptocurrencies. They provide a way for users to take advantage ofthe benefits of digital currencies, such as ability to transfer assets overthe internet, credibly commit to minting schedules, and enable new assetclasses, while also partially mitigating their volatility risks. In this paper, wesystematically discuss general design, decompose existing stablecoins intovarious component design elements, explore their strengths and drawbacks,and identify future directions.