Land records are a vital part of genealogical research. Besides the obvious information of telling where somebody lived they can also give family names and relationships, marriage information, death information, and descriptions of what was on the property.
Deeds are kept on the county level. The owner brought the deed in to the clerk and the clerk copied it, by hand in the old days, and returned the deed to the owner.
There are also federal land records such as those produced by the Homestead Act. This is a page from my great, great grandmother Jane (Malone) Thompson's homestead papers.
The interesting part to me is that she owned a sod house 16 x 18 feet with one door and one window.
The sod hen house was 12 x 12 feet; almost as big as her own home. She also had a well and eight acres under cultivation. Jane was over 70 years old and a widow when she followed some of her children and their families to southwest Kansas.
Another part of the document shows she couldn't sign her own name thus she made her mark.
Land records from most of the United States and some foreign countries are available on microfilm through the LDS family history centers. Although they are indexed by buyer and seller the most amazing stuff is found by scanning the documents. People listed in the document aren't indexed. These people could be prior owners, co-owners, neighbors and spouses.
I always make a list of all the surnames I'm searching in a certain county before I start an in-depth land search. Not just ancestors but spouses and neighbors. And I copy everything. What doesn't seem important at a certain point in your research may be very important later on.
Start digging into those land records and have fun!