Smile

A smile is a facial expression formed primarily by flexing  at the sides of the mouth. Some smiles include a contraction of the muscles at the corner of the eyes  an action known as a "Duchenne smile". Smiles performed without the eye contraction can be perceived as "fake".

Among human smiling is an expression denoting  It is distinct from a similar but usually involuntary expression  known as a grimace. Although cross-cultural studies have shown that smiling is a means of communication throughout the world^] there are large differences between different cultures, with some using smiles to convey confusion or embarrassment.