Hugs and kisses or xoxo is a term used for expressing affection or good friendship at the end of a written letter, email or SMS text message. The common custom of placing X's on envelopes, notes and at the bottom of letters to mean kisses dates back to the Middle Ages, when a Christian cross was drawn on documents or letters to mean sincerity, faith, and honesty.[1] A kiss was then placed upon the cross, by the signer as a display of their sworn oath. It was also used in early Christian history as much of a display of the same. Since most of the common people were unable to read or write, the 'X' was placed on documents, and a kiss placed upon it as a show of their sincerity.[2] The Chi Rho, often represented with the letter 'X', was also used as a holy symbol throughout Christian history as it represented the Greek word for Christ ΧΡΙΣΤΟΣ; this gave rise to the practice of using the letter 'X' for the tradition of displaying a sacred oath.[1][3]
The 'O' is of North American descent; no one really seems to know how it was started. It has been said that when arriving to the US, Jewish immigrants would use an 'O' on documents, not using the sign of the cross, and shop keepers would often use an 'O' when signing documents, in place of an 'X'.[4] Perhaps now it is used as the 'O' being rounded represents arms encircling another, as in an embrace.'X' is used to signify a kiss and 'O' is used to signify a hug.[5][1] The use of 'X' to signify a kiss dates back to as early as 1765.[5][6]
Example from history
One unambiguous example where x is used to represent "kiss" comes from a tragic event in 1905. A seaman aboard the doomed SS Kaliyuga managed to write this final message, where one x is used for each of the family members mentioned:
"Dear Father: Good-bye. I have a bank book in the Cleveland Society of Savings. Good-bye mother, dear sister and brother. xxxx A kiss for all."[7]
This note was found on the body of oiler Charles Beaugrand[8]
.25 which washed ashore several days after his ship sank during a late October storm on Lake Huron.