The widespread use of monograms on household items began in the Middle Ages. They usually appeared as a combination of the initials and a noble coat of arms and were typically placed on personal objects: not for decorative purposes, but to indicate ownership.
By the mid-19th century, the use of monograms was adopted by the middle class. Since they did not have coats of arms, they made do with monograms that were comprised solely of their initials.