The Hydra Head Protocol, hereby simply referred to as Hydra, is a scalability solution on Cardano. What is HydraThe Head protocol presents an isomorphic layer-2 solution that belongs to the family of state-channel solutions. The Hydra Head protocol is therefore considered a layer-2 solution because it is built on top of the Cardano mainchain. In addition, Hydra appears characterized as isomorphic because transactions in a Hydra head share the same capabilities as the transactions running on Cardano. This offers strong security guarantees to participants of a Hydra head, yet limits the total number of participants of a single head.