A consensus algorithm is a process used to achieve agreement among a distributed network, they are designed to achieve reliability in a network involving multiple unreliable nodes.
In the last section, you saw an example of how the proof of work functions to secure a blockchain. The following video explains a different consensus algorithm called Proof of Stake.
Proof-of-stake (vs proof-of-work) (Mar 2018)
Research a different consensus algorithm such as proof-of-importance, delegated-proof-of-stake or proof-of-useful-work.