The title of "Sir" is given to anyone awarded knighthood by the Queen or a member of the royal family acting in her stead. Knighthood can be awarded for military service or to anyone deemed a significant contributor to national life. Members of the clergy and foreign citizens who are awarded knighthood cannot use the title of "Sir."
In order to be granted knighthood, one must be dubbed as such by the Queen. The dubbing occurs during a ceremony, conducted publicly or in private, where the Queen awards knighthood using a sword and by presenting insignia of knighthood. When a clergy member is awarded knighthood, a sword is not used because it is not considered appropriate to the station of the clergy.
Knighthood cannot be bought or solicited and it does not imply military duty to the Queen. The female version of knighthood is known as damehood. Rather than using the title of "Sir," a female recipient may use "Dame". The same rules apply to using the title "Dame" that do to using the title "Sir." The children of a knight or dame are not granted the title on virtue of their birth. Knights are required to earn the title through military honor, scientific achievement, civic achievement, or other invaluable contribution to the country or crown.