In most countries, marriage certificates (or the certificate of marriage) is the official record of a marriage ceromony between two people. In the early 19th century in England and Wales, civil registaretion began which aimed to give a record of all marriages, births and deaths. An official, named the Registrar General, was appointed with overall responsibility to split the two countries into districts of registration.
It was under this system that every marriage (or indeed marriage ceremony) was neccessarily certified with the details stored centrally. By the end of the 19th century, non-conformist and Roman Catholic priests could also issue certificates (and authorise marriage ceremonies).
For more information on death certificates, legal support services, and marriage certificates, please follow the links.