Stacks is a Bitcoin layer for smart contracts, it enables decentralized apps for Bitcoin. Stacks is an open-source project with an ecosystem of independent entities including Hiro System an entity that builds developer tools for Stacks. The Stacks cryptocurrency (STX) was distributed through the first-ever SEC qualified token offering in 2019. The Stacks mainnet went live in Jan 2021, and there are now 50+ startups working in the ecosystem.