The display on the left (it's from Reunion for Mac) is basically a cover page for information about thousands of people. You may browse through it interactively, starting with an individual from the index or a family surname. From there, you can look for the person’s ancestors, spouse, or children. Because there’s so much information, a desktop computer with a big screen will probably be the best option. The displays are not very well suited for portable devices or small browser windows. You may also open the display in a new tab for additional space.
The interactive database is complete for all but one couple of my ancestors through Generation VII, back to about the era of the Revolutionary War. A couple of trails go back to ancient royalty. The available information is of course very thin that far back, but records for some branches are amazingly conserved. Record-keeping was systematic and has been preserved for very stable societies, notably that of Sweden. Of course, the lines going back to British and European nobility have had meticulous and exhaustive study. As things move farther back in time, there is a significant occurrence of interbreeding. This is only inevitable when people lived in small communities for many generations, whether a Swedish farming village or European royalty.
Interestingly, DNA is starting to play an occasional role in resolving controversies. Presumably this will grow exponentially as data bases become larger.
Please feel free to ask me if you have questions about something that isn’t shown here. I encourage people to contact me about areas of original research, because there may be materials or questions beyond those shown here. I regret, however, that I will not be able to accomodate requests for bulk transfers in GEDCOM or other exchange formats.
Updated May 10, 2017