A lie is something that someone says that is not true to make others believe that the lie is the truth. People can have many reasons for lying, such as to hide something or get something, or white lies. Studies show that people usually start lying at the age of two.[1] Some people are pathological liars.[2]
Lying can only be done deliberately (on purpose). If a person says something which is not true, and does not know that it is not true, that person is making a mistake and not lying.
"Repeat a lie often enough and it becomes the truth", is a law of propaganda often attributed to the Nazi propaganda chief Joseph Goebbels. But the description first appeared in Hitler's Mein Kampf, 16 years before Goebbels' use of the phrase. The European Center for Populism Studies says Hitler first used it to describe the behaviour of Jews rather than a tactic he himself advocated.