B1used to say that something has ended: Well, that's it, we've finished - we can go home now.That's it! I'm not putting up with any more of her rudeness.B2used to say that something is correct: You switch the computer on at the back. That's it.
According to sociologists (=people who study the relationships between people living in groups), we are good at lying. As a species, we have developed a remarkable ability to deceive each other (= persuade each other that something false is true). Being able to say things that are not true can help with