what is a duke in royalty

A duke is a title given to a male member of royalty or nobility, either of a monarch ruling over a duchy or as a member of royalty or nobility. It is the highest possible rank in the peerage system. Dukes are ranked below emperors, kings, grand princes, grand dukes, and sovereign. In the United Kingdom, a royal duke is a duke who is a member of the British royal family, entitled to the style of "His Royal Highness". Most princes become dukes when they get married, and some British princes are given the title "Duke" upon coming of age. A woman who holds in her own right the title to such duchy or dukedom, or is married to a duke, is normally styled duchess. The title can either be passed down by a parent and inherited or given as a title by a king or queen. The eldest son of a duke will use one of the duke’s subsidiary titles, whilst other children will use the honorary title ‘Lord’ or ‘Lady’ in front of their Christian names. Currently, there are 24 non-royal dukedoms in the British peerage, and 7 royal dukedoms.