Lisk is a decentralized network, like Bitcoin and Litecoin, which enables developers to deploy their own side chains off the main Lisk blockchain. These side chains are fully customizable blockchains which enable you to change the parameters you want to fit your own blockchain application.
This is similar to Ethereum and QTUM in some ways. With Lisk, the main difference is that the customizable blockchains split into their own separate side chains. This saves developers the grueling legwork of designing something from scratch. At the end of the day, side chains are only decentralized databases of blockchain applications.
Lisk is being developed by a small but quickly growing Berlin-based team. They are led by co-founders Max Kordek and Olivier Beddows who are veterans in the cryptocurrency and development world.