RSK (Rootstock) is a Bitcoin sidechain launched in 2018 that enables smart contract functionality while using Bitcoin as its native asset, addressing Bitcoin’s limited programmability without requiring a new speculative token. Built as an evolution of QixCoin and Ethereum concepts, RSK provides a Turing-complete virtual machine (RVM) that’s highly compatible with Ethereum’s tools and dApps, offering faster transaction confirmations (around 30 seconds) while maintaining Bitcoin’s security through SHA-256D merged mining with over 40% of Bitcoin’s hash rate as of 2019. The platform uses a two-way peg system where Bitcoins become “Smart Bitcoins” (RBTC) on the RSK blockchain and can be converted back without additional costs beyond standard fees, with no new currency issuance since all RBTC originates from actual Bitcoin. RSK currently operates with a federated peg and includes protection against selfish mining through the DECOR+ protocol, while the community has planned future upgrades including storage rent, parallel transaction processing, block propagation optimizations, transaction compression protocols, support for additional VMs, and a hybrid federation/drivechain-based peg system, all documented as RSK Improvement Proposals (RSKIPs) in their GitHub repository, with RSK Labs serving as the primary development company since 2015.