Aeternity is a platform for developing smart contracts founded by Yanislav Malahov, one of the earliest members of the Ethereum team. It differentiates from other platforms which do the same by running smart contracts on "state channels" instead of a blockchain. Smart contracts are normally signed and then executed and verified peer-to-peer. In case of conflict, Aeternity's blockchain can check them for correctness. This relieves the blockchain from congestion and, besides providing privacy for the contractors and reducing costs, it also solves most part of the scalability problem currently afflicting most major smart contract platforms.
It also introduces oracles, which links smart contracts to real-world decision-makers. In many cases, smart contracts depend upon reporting facts which cannot be obtained purely by code, so human (or IoT) oracles are designated to stake their coins in such contracts' results, e.g.., weather conditions or election results.
The platform makes use of both PoS and PoW, although PoS is used exclusively for their delegated PoS-system. Authentication consensus is reached using an ASIC-resistant PoW system called Cuckoo Cycle in which even mobile devices are able to mine efficiently. Thus, Aeternity is a PoW blockchain with a dPoS system for governance.