Court records provide good information, as do church records, county records, property records, cemetery records, headstones and DNA test results. There are many other ways of obtaining information that are just as good. What's even better? Triangulating pertinent information by comparing what you find in one source with information from other sources. Here's an example I just found and it has provided me with a clue that gives me a location in Ireland to begin searching on one of my Irish lines.
I did a Find-A-Grave cemetery search for the name Thomas Doran in Ireland. Of course, I didn't expect to find my ancestors in this search. This is a pretty common name in Ireland and I know my relations named Thomas Doran died and were buried in America. I figured that since the Irish tend to name their children after their father, grandfather and so on, I figured there might be another Thomas Doran that lived and died in Ireland that could be related to me. Of course, I found many Thomas Dorans buried in Ireland. Most of them are in the Dublin area, several are in Wicklow, Louth and a few more in other areas. Even if we assumed my Dorans were from Dublin, there are so many Dorans in the area that it would be pretty difficult figuring out which one(s) I was related to.
That's when I pulled each of them up and looked at surnames of others related to them. For one of them (http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=Doran&GSbyrel=all&GSdyrel=all&GScntry=35&GSob=n&GSsr=81&GRid=128452968&df=all&), who died in 1904, he had a daughter named Margaret Doran, who married a McGowan. If I was related to any McGowans, it's possible I could be related to this Doran. I did a search on my Family Tree DNA match list and found two genealogical matches who are descended from McGowans. They also shared the same part of chromosome one with me! To top it off, one of them also shared with me the same part of chromosome six as many other matches of mine do! Based on the ancestry of these matches, I figured they were related on one of my Irish lines.
Now, none of this makes it 100% certain that I am related to the Dorans from Newcastle, County Dublin, Ireland, but I believe it's a good possibility.
Looking just at Find-A-Grave, there would have been no way I could have determined which of these Dorans I might be related to. Looking just at my DNA matches, there would have been no way I could have determined that I might be related to them on my Doran line since none of them show the surname Doran as their ancestral name since they don't list Doran in their ancestry and I don't have McGowans in my known ancestry.
Again, this is not proof of my relation with this Thomas Doran that died in Newcastle, County Dublin, Ireland, but it gives me a place in Ireland to begin looking for my Doran records. Wish me luck!