A groomsman is one of the male attendants to the groom in a wedding ceremony. The term usher is more common in the UK while the term 'groomsman' is more commonly used in America. Usually, the groom selects close friends and relatives to serve as groomsmen, and it is considered an honor to be selected. From his groomsmen, the groom usually chooses one to serve as best man.
For a wedding with many guests, the groom may also ask other male friends and relatives to act as ushers without otherwise participating in the wedding ceremony; their sole task is ushering guests to their seats before the ceremony. Ushers may also be hired for very large weddings.
In a military officer's wedding, the roles of groomsmen are replaced by swordsmen of the sword honor guard. They are usually picked as close personal friends of the groom who have served with him. Their role includes forming the traditional saber arch for the married couple and guests to walk through.
The most visible duty of the groomsmen is helping guests find their places before the ceremony and to stand near the groom during the wedding ceremony.
Additionally, the groom may request other kinds of assistance, such as planning celebratory events such as a bachelor party, also called Stag Night or Buck's Night; helping make the wedding pleasant for guests by talking with people who are alone or dancing with unaccompanied guests or bridesmaids, if there is dancing at a wedding reception; or providing practical assistance with gifts, luggage, or unexpected complications. Groomsmen may also participate in local or regional traditions, such as decorating the newlywed couple's car.
Bridegroom-men formerly had important duties. The men were called bride-knights, and represented a survival of the primitive days of marriage by capture, when a man called his friends in to assist to "lift" or kidnap the bride, or from the need to defend the bride from would-be kidnappers.
Best man 
The best man is the chief assistant to the groom at a wedding and (along with Maid of Honour) is the third most important in attendance after the Bride and Groom. In most modern, English-speaking countries, the groom extends this honor to someone who is close to him, generally his oldest and closest male friend, or a sibling. When the groom wishes to give this honor to a woman, she may be termed the best woman or best person, although traditionally she would still be referred to as the 'best man'. The bride's equivalent of the best man is the bridesmaid, or the maid/matron of honor. A gender-neutral term is honor attendant. During a wedding ceremony the best man stands next to the groom, slightly behind him. This means that the four people present at the Altar are the religious attendant (such as a Priest), the Bride, Groom and Best Man. This is common in some western countries, although in others the best man and bridesmaid participate on an equal footing.
While the best man's required duties are only those of a friend, in the context of a western white wedding, the best man will typically:
- assist the groom on the wedding day,
- be in charge of the ushers
- keep the wedding rings safe until needed during the ceremony,
- stand next to the groom during the ceremony,
- act as a legal witness to the marriage and therefore sign the marriage certificate, and
- prepare a "Best Mans speech" to be read at the reception.
In various cultures 
The best man, or honor attendants in general, are not universal customs. Even in places where a best man is customary, the role may be quite different when compared to other areas or times.
- In Zambia a best man is expected to lead processions both at the wedding, and at preliminary events. This includes pre-wedding dance rehearsals, at which the best man is always expected to be in attendance, and usually is expected to give an outstanding and outlandish dance-performance on the actual wedding-day.
- In Uganda a best man is expected to guide the newlyweds in the ways of marriage. This means that ideally a best man must be married, preferably to one wife, and should be in position to give sound, tried and tested advice. A best man must be a confidant and be discreet about the details he shares with the new couple.
- In Bhutan the best man presents himself at the wedding as a ceremonial guardian to both bride and groom. Thereafter he entertains the guests, sometimes for several hours.
- In Eastern Orthodox weddings in Greece, the best man is often also the koumbaros, or religious sponsor, and is traditionally the groom's godfather. The koumbaros (or koumbara, if a woman) is an honored participant who crowns the couple and participates in circling the altar three times. In some areas, this person also pays for all the wedding expenses.
- In Ukraine a best man is responsible for guarding the bride during the wedding festivities. When he or the groom steps away, the bride gets "kidnapped" or has a shoe stolen. Then the groom or the best man must pay a ransom in exchange for returning the bride, usually by paying money (which is given to the bride) or by doing something embarrassing.
- In Canadian/American weddings the best man and groomsmen are often required to "jump in" and fix last second problems, such as a missing pocket square or providing a ipod dock to play randomly selected wedding music because the musician did not show up.
Bachelor party 
In the past, the bachelor party was typically scheduled for a convenient evening during the week before the wedding. A type of farewell dinner, it was always hosted, and therefore organized and paid for, entirely by the groom. The dinner was seen as the groom's last chance to entertain his friends as a single man; after the wedding, dinner parties at his home would always be presided over by his wife in her role as hostess.
Common slang names for this event are bachelor party, stag do or bucks' night in different parts of the world. In many areas, this dinner is now most commonly organized by the best man, and the costs can be shared by all of the participants, or all of the participants except the groom, who becomes the guest of honor.
See also 
- T. Sharper Knowlson (2008) . The Origins of Popular Superstitions and Customs (Forgotten Books). Forgotten Books. pp. 100–102. ISBN 1-60506-458-0.
- Leopold Wagner (1995). Manners, Customs and Observances. Omnigraphics Inc. pp. 61–62. ISBN 978-1-60506-798-8.
- Chisholm, Hugh, ed. (1911). "Bride". Encyclopædia Britannica (11th ed.). Cambridge University Press.
- http://www.rhymingspeeches.com/best-man-duties/ Best Man Duties
- "International Wedding Customs". Archived from the original on 2008-05-03. Retrieved 2008-06-20.
- "Essential Guide to Ukrainian Wedding Traditions!". What's On Kiev. Retrieved 2008.
- Post, Emily (1922). Etiquette in Society, in Business, in Politics and at Home'. Funk & Wagnalls Company. pp. 335–337.
- Post, Peggy (2006). Emily Post's Wedding Etiquette (5 ed.). London: Collins. pp. 183–184. ISBN 0-06-074504-5.