People had been kicking balls about for thousands of years before the 1860s, but every village had different rules. Some games allowed you to pick the ball up. Some let you tackle people. Some had no real goals at all. In 1863, a group of English clubs met in London and agreed one common set of rules. They called their group the Football Association - and that is where 'soccer' (short for 'as-soc-iation') comes from.
Britain has some of the oldest football clubs in the world. Sheffield FC, founded in 1857, is the very first. Other famous clubs - Manchester United, Liverpool, Arsenal, Celtic, Rangers - go back well over 100 years. The English Premier League is one of the most-watched sports leagues anywhere on Earth.
What makes football so popular? It is amazingly simple. You only really need a ball and something to be the goalposts. People play on streets, beaches, dust pitches, fields and proper stadiums. The world's best players started in exactly the same way as the children playing at break right now.
The men's and women's national teams of England, Scotland, Wales and Northern Ireland play separately. The famous Wembley Stadium in London is one of the most-loved football grounds in the world. Around 90,000 people can fit inside it.