Well as far as i know Cardano is the first protocol to incorporate Ouroboros, the ground breaking proof of stake algorithm. The IOHK team employed a “first-principles” approach, driven by peer-reviewed academic research to build Cardano from the ground up.
This uniquely collaborative effort steadily constructed the most precisely engineered cryptocurrency yet, a product that brings together such disciplines as distributed systems, mechanism design and cryptography. The result is the first cryptocurrency to be based in Haskell code, an industrial strength product that delivers the resilience necessary for mission-critical systems, in this case, securing investment.
RE: What is Cardano ADA? Programmer explains.