This passage is from "British Council".

The price of love

For most of these romantic people, Valentine's Day means spending money. British people spend much less than Americans. The average Brit spends £28.45, while the average American spends $221.34 (approximately £170.81). Interestingly, in the UK, all three adult generations are likely to buy something for Valentine's (around 68–69% of them). But in the USA, millennials spend slightly more than Generation X, and both spend almost a third more than baby-boomers. Across all generations, on both sides of the Atlantic, men spend more money than women.

 The beginning of modern Valentine's Day 

Today Valentine's is mainly celebrated in Canada, Mexico, France, Denmark, Italy and Australia as well as the USA and England. But it's the USA where the celebration really became mass market, because of a woman called Esther Howland. She became known as the 'mother of Valentine's' after she created a successful business making and selling greetings cards in the 1840s. She got the idea from valentine cards from Europe that were decorated with lace and flowers and were very expensive. Then, in the early 1900s, two things happened that meant valentine cards became really popular: cheap printed cards were made by the greeting cards company, Hallmark, and the price of postage stamps fell.

Vinegar Valentines 

At about the same time as this, another kind of valentine card was popular. 'Vinegar valentines' were nasty, anonymous cards that people sent to someone they didn't like. This pre-social media way of trolling people was popular for a hundred years, but not many examples of the cards are in museums today. Museums have big collections of traditional valentine cards, but it's no surprise that not many people kept an unkind valentine card

 Further back in history 

Valentine's Day has been celebrated in some way for 600 years. As far back as the 17th century, people gave cards or presents, but the very first valentine messages were written down in the 1400s. In 1415, the Duke of Orleans in France sent his wife a Valentine's Day letter while he was in prison in the Tower of London after the Battle of Agincourt (阿金库尔战役). It is the earliest example of a written valentine message. However, the exact history of Valentine's Day is not known because there were three saints with the name Valentine. One story says that Valentine was a priest. He performed marriages at a time when the Emperor thought that single men were better soldiers than married men. The Emperor was so angry that he punished him with death. Another story says that Valentine helped Christians escape from Roman prisons. A third story says he sent a letter to a girl while he was in prison and signed it 'From your Valentine'.