Stacking is an innovative mechanism that rewards STX token holders for participating in the Stacks blockchain’s consensus process, called Proof of Transfer (PoX).
STX holders who participate in Stacking are called Stackers. Every time a new block is mined on the Stacks blockchain, the protocol sends BTC committed by miners to Stackers as a reward for adding value to the network. All eligible Stackers are rewarded with BTC approximately once per Stacking cycle (e.g. 7 days, though the exact duration is prone to change).
The Stacks Earning Model can be used to estimate potential BTC rewards from participating in Stacking.
Stacks holders can participate in Stacking with v4.x or greater of the Stacks Wallet, as well as applications and services provided by other entities.
Stacks holders need a dynamic minimum amount of STX to participate directly (an estimated 100,000k STX upon mainnet, though this amount is prone to fluctuate based on overall participation and supply). Those who don’t possess that minimum can participate in third-party Stacking delegation services, which allow them to pool their holdings with others for joint participation.
More details on Proof of Transfer, STX mining, and Stacking are available in this blog post and this draft whitepaper.