In the United Kingdom royal dukes trump all other aristocrats. Prince Charles is a royal duke and Camilla, as a royal duchess is also at the top of the tree. After this, there are duchesses, marchionesses, countesses, viscountesses and baronesses, in descending order. These are invariably the wives of dukes, marquesses, earls, viscounts and barons respectively. However, there are a large numbers of baronesses in their own right as they can be created as life peeresses in their own right and can therefore sit in the House of Lords (which is the upper chamber of the Houses of Parliament).
Any female can obtain a title and become an aristocrat by marrying a titled man but it does not work in reverse.
The terms 'peer' and 'aristocrat' are collective terms for all the ranks of nobility listed above. Royalty is above any rank of nobility and consists of the monarch (king or queen), princes and princesses.
On formal occasions, peers wear ceremonial robes lined with ermine with gold braiding which differs to show which rank they belong to. At coronations, every peer also wears a coronet, with distinguishing marks which again show which rank the wearer belongs to.
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