Laws are made by MPs. Someone in parliament will suggest a new law, or an alteration to an existing one, such as changes to punishments for carrying illegal guns.
Sometimes new laws are needed to ensure that the UK complies with International or European Law. The Human Rights Act 1998 and the Freedom of Information Act 2000 are recent examples of this.
This draft - or proposed - law is called a Bill. It must be discussed in the House of Commons and in the House of Lords.
When this is done and the new law has been agreed, the Queen must give her approval. The Bill then becomes an Act.