smile

A universal signal of friendliness, happiness, or amusement. While usually positive, it can carry complex social layers depending on the intensity and authenticity of the expression. Distinguished from 'grin' by its typically softer, more subtle nature. A smile is often a gentle gesture of kindness or politeness, whereas a grin implies a wider, more mischievous, or triumphant display of teeth. In social contexts, it can function as a tool for diplomacy (the "polite smile") or a mask for hidden emotions (a "forced smile"). It is the primary non-verbal cue used to put others at ease or signal agreement.