Human beings can recognize a smile from more than 300 feet away (almost the length of a soccer field). This is an evolutionary trait developed to identify friend from foe. But smiles are a tricky thing to decipher. They can be used to express, hide, or even disguise feelings.

If the smile of a friend or a colleague perplexes you, look no further. This Bright Side article will help you recognize and understand the underlying motive behind the most popular types of smiles that were identified based on research conducted by the 19th Century neurologist Duchenne de Boulogne.

The closed-lip smile

The preferred smile of politicians, it indicates that the person knows something of importance to you but has no plans of sharing their secret. This smile is pretty easy to identify, as it is similar to the feeling it portrays. You can see the smile, but the closed lips will never reveal the teeth.

The twisted smile

When someone is bewildered, it shows in their smile. One side of their lips tilts upwardsignifying that the future has something good in store for you, while the other side tilts downward meaning that not everything is gung-ho.

The forced smile

There are days when you are in no mood to smile and yet the situation requires you to present a smiling face. Or someone cracks a not-so-amusing joke and expects if not your laugh, at least a smile. The soulless smile that you then flash is the forced smile. While your lips try to look happy and smiling, your eyes betray it.

The genuine smile

The wide grin and the contours around your eyes are a giveaway. It announces your happiness to the world. This smile is also contagious, it makes everyone around happy too.

The sneer

This smile reminds us of Draco Malfoy, the mocking and somewhat conceited smile that oozes with disdain for others. This smile with the lips slightly curled upward and the eyes beaming hatred is not hard to recognize. Anyone who comes across this smile will immediately feel it. It’s certainly the preferred smile of narcissists.

The smug smile

With the lips pressed together tightly, and one side a bit more raised than the other, this is a very complex smile to decipher. Depending on the situation and the person it can be a sign of arrogance or satisfaction. It can also be used flirtatiously in a very effective manner.

Open mouth smile

The open smiling mouth might be great for photographs and selfies, but it might not look so good if used as the preferred smiling technique. But there is no denying that this smile does radiate overflowing happiness.

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Flirtatious smile

This smile—though very similar to the smug smile, with the difference being that the lips can be bitten or licked—is very enticing. It is incredibly mysterious, sexy, and inviting. Also, it makes the person flashing this smile look more attractive.

The Pan Am smile

The fakest of all smiles, this smile is named after the smile that the Pan Am flight attendants were trained to flash at every traveler. While the lips open up trying to smile and flash the teeth, the eyes remain expressionless and rigid. This smile conveys no emotion and shows that the smile is just customary.