LIfe peerages are awarded for life only and the titles are not passed onto heirs. They are awarded by the Queen on the advice of the Prime Minister.
Many life peers are political appointments to ensure political presence of the main political parties in the House of Lords.
The Archbishops of Canterbury and York usually get life peerages on retirement, as do former Speakers of the House of Commons, Prime Ministers, Home, Defence and Foreign Secretaries and Chancellors.
The 1999 House of Lords Act cut the number of hereditary peers entitled to a seat in the House of Lords from over 700 to 92 and ended the right to pass membership of the Lords down through the family.