Following the popularity of the BBC show Who Do You Think You Are genealogy has never been more popular in the UK, which is perfect timing for the 2011 Census of England and Wales that takes place on March 27.

For the first time householders have the opportunity to submit their census answers online.

25 million household questionnaires, based on a newly developed national address register, will be posted in the run up to the 2011 Census. These should arrive in every residence by the middle of March.

But the Internet, which has revolutionised the family history industry, is at the forefront of the new data gathering.

People will be able to complete the questionnaire online from March 4. The paper questionnaire has a code on the front. This will be the key to unlock the online questionnaire.

Householders should then go to, 'Click to fill it in' and follow the on-screen instructions.

New web services have been created for the online questionnaire, and an online help centre will provide advice and guidance for completing the questionnaire.

An accessibility area on the website will provide video and audio assistance, in English and Welsh, for people who are visually impaired or deaf.

A census is a count of the population, and one takes place in the UK every 10 years since 1801 (with the exception of 1941).

It gives a richly detailed snapshot of the population as it stands on one day.

There will be separate censuses across the UK on March 27, 2011 - organised by the Office for National Statistics (ONS) in England and Wales, the General Register Office for Scotland and the Northern Ireland Statistics and Research Agency.

In addition to being an invaluable resource for family historians the census results play a vital part in the calculation of resource allocation to regional and local government service providers.

It is a legal necessity for all households to return the census questionnaires or submit online.

People who have not returned their questionnaire by April 6 will be called by a census collector soon afterwards.

A month before the 2011 Census takes place the UK's largest family history event Who Do You Think You Are? LIVE 2011, sponsored by and The Telegraph, takes place at London's Olympia at the end of this week: 25 - 27 February 2011.

The event is a one-stop-genealogy-shop where visitors can discover the landscape of their past guided by over 200 exhibitors; ranging from The Society of Genealogists and The National Trust to The Royal Artillery Museums and Family Tree DNA.

Celebrity speakers include television presenter and horticulturalist Monty Don and actor Hugh Quarshie, who will recount tales from their own past. Blackadder actor and archeologist Tony Robinson will also appear at the show to discuss the 1911 Census and how it can be used to piece together a family tree.

Although it is a relatively new tool, DNA testing is now used to confirm family ties where no conventional record exists. At the show renowned international experts will discuss how to apply the latest advances in genetics to help piece together a family tree.