Without this kind of background information, you will have trouble identifying your ancestor among the thousands of others.
When you have done your basic genealogy and built a skeleton family tree, it is time to investigate more specialised websites, for example, those containing military or employment records, parish records or wills. But you will need some basic information to make best use of what they have on offer: there is no point in paying to look for details of your great grandfather's military career if you don't know his full name, date of birth and the force in which he served. Without this kind of background information, you will have trouble identifying your ancestor among the thousands of others. In other words, you need to use genealogical sites in the right order to ensure that you get the most out of them.