Our culture celebrates friendship on momentous occasions. Families and friends gather to celebrate births, birthdays, graduations, weddings, anniversaries, retirements, and deaths. Hit a milestone, get a party.

Valentine's Day is a slightly different kind of commemoration in that everyone expresses affection to close and/or romantic friends on the same day, even though the friendships typically continue across the year. Valentine's Day on February 14 has existed for hundreds of years in various cultural formats—although it's still problematic which noteworthy Valentine of several candidates is responsible for the day's title. The hearts and cupid icons that incorrectly suggest the nature and source of romance are obviously remnants of ancient beliefs.

Valentine's Day originally involved the exchange of affectionate letters, but by the middle of the 19th century the exchange had shifted to printed cards and gifts (such as candy, flowers, and jewelry). And just as we've recently seen duplicated December letters and cards morph into electronic greetings, we can probably expect the Valentine's Day exchange to shift eventually from paper to email.