Mostly just a day set aside during a time of year when most people are feeling the blues and it encourages people to take a day to celebrate the relationship you are in to show appreciation to a partner. Since most people are also in a spending slump this time of year, it also brings a spending jump back to the economy after the big spending spree of Christmas season. It serves two purposes this time of year. One is a reminder to show appreciation to a person you love, the other is to bring an upward jump in spending for businesses. It helps bring smiles during the hardest time of year when many people are struggling with winter blahs.