St Valentine's Day is on 14 February. There are a number of stories associated with St Valentine; the most likely is that he was an early Christian bishop (3rd century) who refused to give up his religion; it's also been suggested that he made a point of performing Christian marriage ceremonies, which could be why he is considered the patron saint of lovers. However, there was already a Roman tradtion associated with lovers on 14 February, so that may have played a role too.

However it started, Valentine's Day is now more popular than ever. The usual custom is for lovers to give each other cards and small gifts; typically, a Valentine gift would be something romantic rather than practical. in the past it was common to make a card or other greeting yourself, but nowadays most people buy them.

Another tradition associated with this day is that it's OK for women to propose marriage to men (of course, there's nothing to stop them doing this on any other day, but some people like to wait for Feb 14 and make a special occasion of it.)