Tezos uses a form of proof-of-stake consensus mechanism, as opposed to the proof-of-work system favoured by Bitcoin. You might see the particular type of Proof-of-Stake referred to as Liquid Proof of Stake, or LPOS. Network nodes which validate the stake are known as ‘bakers’, in Tezos parlance.
The way that the blockchain is governed means that upgrade proposals can go through once they’ve received a favourable vote, which allows Tezos (in theory) to avoid some of the hard-forking that’s affected other altcoins.