MPs debate private members' bills - BBC News
The House of Commons examines bills set forward by MPs, including a bill on organ donation.
They were created in 2004 to give same-sex couples - who at the time couldn't marry - similar legal and financial protection to a marriage. They weren't available to mixed-sex couples.

Then, the Marriage (Same Sex Couples) Act 2013 legalised same-sex marriage in England and Wales and the Marriage and Civil Partnership (Scotland) Act 2014 did the same there.

Since then, same-sex couples there have been able to choose between marriage or civil partnerships - except in Northern Ireland, where they are still not able to marry.

But the opposite didn't become true - mixed-sex couples didn't get the right to a civil partnership. That's what's now set to change.

There is no requirement for a ceremony to take place or to exchange vows - unlike for a marriage - but you can do so if you wish.