What is the 'Lemming effect' in psycology?

This refers to a phenomenon wherein crowds of people, across various fields of life, exhibit a certain kind of behaviour for no reason other than the fact that a majority of their peers do so. Many psychologists even argue that human beings are conditioned by nature to follow the larger group instead of undertaking the risk of independent thought and action. It is named after the popular myth of rodents called lemmings found in the Arctic regions that are supposed to exhibit herd behaviour, so much so that they follow each other even when it leads them into some obviously dangerous situations that could cost them their lives.