Band Protocol is an oracle that brings an addition to the crypto word with their mechanism of connecting externa data source and API with smart contracts. You can utilize their DPoS staking mechanism (i.e. as an delegator you could earn BAND). The main problem is (comparing to Chainlink) it only works with inferiors API. It is slower (own blockchain slows oracle function), use full node exposure mechanism (randomness), lack of any important development. I would prefer Chainlink before Band Protocol.