Civil registration of births, marriages and deaths did not begin until July 1837. At that time England & Wales was subdivided into administrative areas known as registration districts. Within each district a registrar took responsibility for the recording of births, marriages and deaths.
Four times a year all the registrars for England & Wales collated them into a single countrywide index, arranged alphabetically by surname.
The indexes to the registers are quarterly rather than annual in scope - the four quarters being known as March, June, September and December. Each of these covers the month itself and the two preceding months, as follows:
•January, February, March registrations in the March quarter
•April, May, June registrations in the June quarter
•July, August, September registrations in the September quarter
•October, November, December registrations in the December quarter
These can be searched by selecting 'Search' in the top navigation bar, and then selecting 'Birth, Marriage and Death' from the drop down menu. This will then bring you to a new page, along the the left hand side you can filter the type of record e.g. parish or civil.