Indexes of Births, Marriages and Deaths / Census information
The basis of identifying your ancestors and arranging them into a family tree will be, at least initially, the information provided by the government’s registration processes and census data. As you move back in time to the period before civil registration then church records become the main source of information.
Once you have a skeletal family tree it is time to ‘put flesh on the bones’ i.e. not just when and where they lived and died but how. This involves military, occupational, and criminal records among others.
There are many groups and societies that can help with your research, from national and international groups to local societies (like SFHS). There are also specialist groups concentrating on various aspects of genealogy.
With the diverse population we have in the UK it is quite likely that your search for ancestors may take you to other countries. There are many sources that can help in taking your search overseas.