When wearing a double-breasted suit, you should generally button up all the buttons. When wearing a single-breasted suit, if it has two buttons, only button the top button; if it has three buttons, button the middle button or the top two buttons. In some informal situations, you can wear it unbuttoned.

When wearing a suit, shirt cuffs must be buttoned. There is usually a buttonhole on the lapel of a suit, which is called a flower-arranging eye. It is used to place flowers when attending weddings, funerals, or grand banquets or ceremonies. People in China generally do not have this habit.

It is not advisable to put too many things in the pockets and trouser pockets of the suit. It is best to put things in the inner pockets on the left and right sides of the suit. There is a pocket on the outside of the left chest of the suit, which is used for inserting handkerchiefs for decoration. It is not suitable to insert pens or place other things in this breast pocket. Extended information

Before the emergence of modern suits, the suit worn by modern Western men for business occasions consisted of a long and thick black coat called a frock coat. Until the end of the 19th century, Americans began to wear lighter jackets that only reached the waist, called sack suits.

This became the standard daytime attire for informal, non-work occasions, and even the most unpretentious men had a suit like this to wear to church on Sundays. Before World War II, this simple suit was worn with a vest.

On the other hand, evening suits also developed an informal look. The original tuxedo evolved into a small evening gown. Today, evening gowns have even replaced tuxedos as the standard attire for evening occasions, while tuxedos with a longer history are only reserved for the most solemn occasions, such as banquets, music concerts, honoring ceremonies, etc.

Formal attire during the day is a morning coat. Although modern occasions are generally less strict with red tape, depending on the etiquette required for attending the occasion, the dress code should be stated on the invitation.

Reference: Baidu Encyclopedia-Suits