Proof of activity (Proof of Activity, PoA) is a hybrid consensus scheme that combines elements of two basic algorithms: Proof of Work and Proof of Stake. The goal of such a combination is to take the strengths of each approach and smooth out their drawbacks, increasing the security and resilience of the blockchain network.

The process begins on the Proof of Work principle: miners compete to create a block template by performing computational work. However, at this stage the block does not yet contain transactions. Then the Proof of Stake mechanism comes into play: to complete and confirm the block, the system selects a group of validators from among coin holders, with the probability of selection depending on the size of their stake. Only after the block is signed by the selected participants does it become part of the chain.

Why a hybrid approach is needed

• Reducing the risk of attacks through the combination of two protection mechanisms;
• Distributing the reward between miners and coin holders;
• Encouraging participants to hold coins and support the network;
• A balance between computational costs and economic motivation.

Thus, Proof of Activity seeks to combine the reliability of computational protection with the economic interest of holders, which makes it one of the examples of hybrid solutions in the development of consensus technologies.