These are two smart contracts that provide basic, non-custodial escrow functionality on the blockchain. Escrow is a bare-bones escrow contract, while EscrowTapped additionally allows the deployer to set an escrow / dev fee.
While a non-custodial escrow service may not guaruntee that either party will not stiff the other, it takes the incentive out of doing so. To quote Satoshi:
Imagine if gold turned to lead when stolen. If the thief gives it back, it turns to gold again.
For more, read Satoshi's full post on the original bitcointalk thread.
These contracts can be deployed on EVM compatible blockchains like Ethereum. Visit the online IDE Remix to interact with the contract locally or deploy it to a blockchain.
To interact with the contract on Etherscan simply paste the deployed contract address into the serach bar to find the instance, then navigate to the Contract tab.