A genealogist establishes a family tree based on documents. Each member on your family tree has documents available to establish milestones in their lives. For instance, birth, death, and marriage certificates give us a lot of information. Some family members did not leave much of a paper trail. If a relative died young, never married, never owned land, and so forth, they will be harder to trace. Sometimes they establish a nickname as adults and the researcher is searching under the lawful name they were given. Genealogists refer to these individuals as “brick walls” as they are not easily traceable.