The most basic definition of genealogy is “the study of family history and descent”, from genealogy.about.com.
Val Greenwood’s definition: “Genealogy is that branch of history which involves a scientific study for the determination of family relationships.” The Researcher’s Guide to American Genealogy. 3d ed., pp. 8-9. (Emphasis in original statement.)
Family history has a more encompassing definition. Creating a family history means placing each individual and family in a social, cultural, economic, and religious context within their lifetimes. This means going beyond just collecting names and dates and finding out who we are descended from. It means studying the entire family over a period of time, discussing each family group and person and how they fit into a larger historical picture.
Elizabeth S. Mills, in an article in the National Genealogy Society Quarterly also defines genealogy and genealogists, striving to bridge a gap in public perceptions of the hobby and the profession. One of her definitions of a genealogist is “generational historian,” meaning those who “value the difference between gathering names and reconstructing lives.” (National Genealogical Society Quarterly: Centennial Issue 91 (December 2003): 260-277. p. 272)
Being a genealogist means applying analytical and documentation skills beyond most generally accepted history and social science standards. This requirement means being able to decide which one of two people with the same or similarly spelled names is the correct ancestor for a particular family group and using the best evidence available to document the conclusion.
Accepting as truth commonly available or undocumented statements is a mistake many “family tree climbers” (E. S. Mills, same citation as above) and early compilers of family information have made. These statements should be treated as clues for further research into direct, original, and primary sources.
Modern genealogical research standards are discussed in several of Mills’ books and articles (Evidence!, among them), and the BCG Genealogical Standards Manual.