Vitalik Buterin created a new platform for developers to build decentralized applications on, shortly after.
Nick Szabo introduced smart contracts in 1994, however Ethereum revolutionised the technology by allowing them to be deployed on the Ethereum Network.
When it comes to cryptocurrency, you can think of smart contracts like smart money.
People can now program money. With smart contracts, we can give money directions and instructions.
With traditional contracts, it requires the involvement of one, or multiple third parties before the action of the contract can be executed. (example below)