What is the role of oracles in smart contracts? Can you provide one example of an oracle used in a smart contract?

Oracles deliver reliable data feeds from the outside world to the smart contracts. For example: Assume that Alice and Bob want to bet on an outcome of a sports match. Alice bets 20$ on team A and Bob on team B, with the total 40$ held in escrow by a smart contract. When the game ends, how does the smart contract know whether to release the funds to either Alice or Bob? The answer is it requires an oracle mechanism to fetch accurate match outcomes off-chain and deliver it to the blockchain in a secure and reliable manner.