The British Peerage is a well-known system of nobility existing in the United Kingdom.
There are five ranks:
There are two types: hereditary peerages and life peerages. Life peerages honour a person’s accomplishments, the peer holds the title only for his lifetime; it is not passed on to offspring.
The hereditary peerages are passed to the next generation following the law of primogeniture. That is, that they are inherited by the eldest son (even if that child has an older sister). It there are no male heirs, the title ceases to exist, or becomes extinct.
Occasionally, a title may be set up in such a manner that it can descend through the female line as well, but this is highly unusual. (A notable case was the late Earl Mountbatten of Burma, who had no sons and petitioned the monarch to allow the title to be inherited through his daughter.)
A woman may sometimes be elevated to the peerage in her own right. Although a (male) peer’s wife receives a courtesy styling, a peeress’s husband does not.