What is the most popular consensus mechanism?

Can you please elaborate on what the most popular consensus mechanism in the cryptocurrency world is? I'm curious to know which mechanism is widely adopted by blockchain networks and why it has gained such popularity. Additionally, I'd like to understand its key features and advantages over other consensus mechanisms. Is it scalable, secure, and efficient? And how does it ensure that all participants in the network can agree on the state of the blockchain without the need for a central authority?