Hereditary Peers inherit their title and consist of five ranks: Duke, Marquess, Earl, Viscount and Baron. Peerages may become extinct or fall into abeyance, but so long as there is an heir, the title will continue. Stage one of the House of Lords Act 1999 removed the entitlement of most of the hereditary Peers to sit and vote in the House of Lords, and of the 92 hereditary Peers who retain their seat in the Lords, 75 were elected by their fellow hereditary Peers.

There are three types of Lord: Life Peers (of which Law Lords are members), Hereditary Peers and Spiritual Peers.

• A Life Peer is someone who has a noble title but it is not hereditary- the title does not automatically go to his heir when he dies.
• A Hereditary Peer is someone who has a noble title but it is hereditary- the title will automatically go to his heir (typically his oldest son) upon his death.
• The Lords Temporal are Peers (Life or Hereditary) who are sitting members of the House of Lords in Parliament.
• The Lords Spiritual are high ranking bishops from the Anglican Church who also members of the House of Lords.

There used to be over 700 hereditary Peers in the House of Commons, but after stage one of the House of Lords Act 1999, passed by the Blair government, there are 92 hereditary peers left. However, some peers have died recently and their number is around high eighties.

As of April 20, 2012, there are 818 voting members of the House of Lords, of which about 701 are life peers, 92 are hereditary peers who sit in the House due to being elected by their fellows and 25 are bishops . 21 of these are on leave of absence.