Adoption is a process whereby a person or couple can become the legal parents of a child.
In the UK it has always been legally possible for gay people to adopt. However this only applied to unmarried people or to married couples. If a same-sex couple wished to adopt, legally only one partner could be the adoptive parent.
In December 2005, the Adoption and Children Act 2002 came into effect in England and Wales. This allowed unmarried couples, including same-sex couples, to apply for joint adoption. The Adoption and Children Act (Scotland) 2007 came into effect in 2008 in Scotland and had a similar effect.
Northern Ireland has not yet followed suit, and only single people or married couples can adopt. This has the paradoxical effect that a single person in a gay relationship can adopt, but people in civil partnerships cannot, either as a couple or as individuals. In October 2012 a court ruled that the Northern Ireland ban on adoption by unmarried couples and civil partners was unlawful.