During the Middle Ages, few people could read and even fewer coul write. On occasion, however, they had to sign an important paper. In this case they would make an "X," often in some distinctive way.
To give further credence to the document, a solemn kiss was placed on the X.
Over time, the X came to stand for a kiss, according to the Washington Post, but the X also stood for blessing in centuries past.
Though people sign with their names today, the X tells the receiver to visualize that kiss — not for the document, but for the receiver.
But that is one tradition that may come to an end. The X (accompanied by the more mysterious O, denoting a hug) are being replaced entirely by emoticons or even video images. Along with the decline in paper messages, the traditional XO is probably history.
