Scientists are divided over why humans kiss, although we are not the only species that do it. It could be a way to gather information about the person we’re sharing a long, sloppy one with, through the senses of smell and taste. Another theory is that a kiss reinforces feelings of trust and intimacy.

Whether it’s an act of seduction, a warm snuggle or just a friendly peck, there’ll be lots of it happening on Sunday, which is Valentine’s Day.

To mark the romantic occasion, US photo stock agency Getty Images has curated a “kiss” collection from its archive of 80 million photos. Here we present a few of them.