Lines or creases that appear on the sides of the mouth and extend toward the nose, commonly known as nasolabial folds. These lines become more visible when a character smiles or laughs.
In artwork, smile_lines are often used to convey expression, age, or realism. They may be subtle or exaggerated depending on the art style. In anime and stylized art, they are sometimes simplified as short curved lines near the corners of the mouth.
