Delegated proof of stake (DPOS) is a family of consensus mechanisms for blockchain networks. It makes use of witnesses or leaders, often referred to as "delegates", who have approval voting ability to resolve consensus issues. DPOS was created by Dan Larimer in 2013 for implementation in the Bitshares blockchain.
Witnesses or block producers are selected to secure the cryptocurrency network by signing each block, and then approve them through a voting system. Witnesses cannot, however, sign random blocks, and need a witness to have signed a previous block. If witnesses don't produce, they can lose their job on the network or the benefits of the network in the future.
One advantage of DPOS is that it does away with the need to wait until a number of "untrusted" nodes have verified a transaction before it can be confirmed. Thus, this layer of technological democracy offsets the negative effect of centralization.
Delegated proof of stake has been criticized for having increased centralization due to the concentration of power among the leaders or witnesses in the system.
Delegated Proof of Stake: Features and Tradeoffs - Multicoin Capital
Delegated Proof-of-Stake (DPOS)
Seeking Consensus on Consensus - DPOS or Delegated Proof of Stake and the Two Generals' Problem -- Steemit