Aeternity is a cryptocurrency based on Ethereum. Its primal idea is to improve the scalability of smart contracts and decentralized applications.
The main feature that defines Aeternity is moving smart contracts procedures out of the blockchain and taking it to the private channels of the contract-involved agents. Those channels existence takes a lot of stress off the main blockchain. It also helps with privacy problems keeping all the information inside of the private chain. Aeternity also has a feature of decentralized oracle that would make outside data immutable in the Aeternity blockchain.
Aeternity uses a hybrid of Proof-of-Work and Proof-of-Stake algorithms. It uses POF as a mining consensus protocol and a POS to govern the Aeternity ecosystem based on proportions of AE owned by users. Aeternity aims to get mobile users into the network by making new mobile dapps and blockchain features easy to use.