All historical research benefits from searching old newspapers. In genealogy, you never know what you might discover about your relatives in the newspaper. Patrons at the reference desk are often skeptical about using newspapers in genealogy research: "my great-grandmother wasn't famous, why would she be in the paper?" You don't have to be famous, or infamous, to show up in the newspaper, which publishes much more than just the news. Newspapers can be one of the most important resources in genealogy research, and provide dimension, color, texture, and character to the names and dates on a family tree. There is an old saying, that "journalism is the rough draft of history." Somewhere in that manuscript, you might discover information about bygone relatives.
Note that this guide expands and updates the Library's prior guide, Conducting Genealogical Research Using Newspapers, published in 2014.