We all think about Valentine’s Day as a day of love when couples exchange gifts and a few brave people ask their crush to be their valentine, but where did the holiday actually originate?

Though Valentine’s Day now is a mostly nationally celebrated holiday, with no religious affiliation, it began as a celebration of Saint Valentine. However, the identity of “Saint Valentine” is fairly disputed. There are three Catholic saints with the name Valentine or Valentinus, and all of them were martyrs.

According to History.com, the first Saint Valentine was a priest in Rome in the 3rd century CE. He rejected a decree by Claudius II outlawing marriage of young men for the growth of the military and wed young couples in secret, hence his association with love. He was executed for this action.

The second was a saint from the same time period and place who was also executed by Claudius II. However, he did not promote romance as much, and instead was martyred for preaching Christianity in Rome, which was illegal at the time.

The third and final possible namesake of Valentine’s Day was killed while helping to release imprisoned Christians in Rome. He’s known for sending the first “valentine” to a girl who visited him when he was in prison himself.

Originally, St Valentine’s Day was not associated with love but instead one of the many feast days celebrating saints. During the Middle Ages, however, February 14th was considered the start of the mating system for birds, giving the day a romantic association.

Sending valentines became popular for both royalty and commoners, and has continued for hundreds of years, evolving into the holiday we know and love (or hate) today.