Obituary is from the Latin obit, meaning death. The word obituary has been used to refer to published death notices since the 18th century.
British Inspiration: Although brief announcements of deaths were published in America as early as the 16th century, it took another 300 years and some impetus from the British (who beat us to the punch) for the longer, more-detailed accounts to appear in the press.
All About Prominence: Obits have historically been penned about people like soldiers, public servants, celebrities and adventurers because, according to historian Mitchell Stevens, the audience hangs with such interest on the details of their lives and, unfortunately, their deaths.
Mood-ometer: Over time, obituary style has reflected the frame of mind. Accounts of deaths of frontiers men and women emphasized value of life; those of Civil War soldiers were often sentimental and religious.