If you live in an English-speaking part of the world, you probably learned very early that seeing x’s and o’s at the end of a letter or correspondence meant “kisses” and “hugs.”

Have you ever wondered why, though?

It turns out the practice has been around since the Middle Ages, but it’s origins are harder to pin down.

Dr. Laura Wright of Cambridge University thinks it has something to do with the Greek letter ‘X’, which is pronounced ‘ks.’

Other researchers disagree, though, stating that the Greek word for Christ begins with an X, and the letter was used to symbolize the Christian faith.

Many people in the Middle Ages were illiterate and would sign X to signify their name on official documents.

It would also signify a person’s devotion to Christianity.

These marks were often physically kissed – out of love or out of loyalty to their religion.

Sealing a message, signed X, with a kiss was common and cemented the connection between the letter and actual kisses.

The religious connotation faded, but when the X came to exclusively represent kissing is still up for debate.

According to the Oxford English Dictionary, the first known use of X’s as kisses was in a 1763 letter written by naturalist Gilbert White.

He was also referencing religion in the missive, though, so some think it was representative of Christianity, not smooches.

By the time Winston Churchill wrote a letter to his mother in 1894, though, the slang was established.

“Please excuse the bad writing as I am in an awful hurry. (Many kisses.) xxx WSC.”

If Churchill did it, there’s nothing wrong with carrying on the tradition.

Not that anyone would want to get rid of it anytime soon.

If you thought that was interesting, you might like to read about the mysterious “pyramids” discovered in Antarctica. What are they?