Sharp and narrow points to the collar for a slimming effect for various face shapes. The broad collar covers more of the neck, giving the more formal appearance. Additionally, a broad collar allows more room for thick and wide neckties.
Where necessary, you can make a long neck appear shorter by wearing a wide collar, and vice versa with a short neck being made to look longer with a narrow collar. The collar importance cannot be stressed enough since the perfect shirt collar frames a man’s face, compliments his face shape and completes the look. It has traditionally been used for formal and social occasions and works well worn with medium sized ties as compared to left open.