soccer is a noun that means a team sport played primarily with one's feet, in which two teams of 11 players each attempt to score goals by placing a ball in the opposite goal. The rules of soccer are quite simple
each team must try to score by kicking or heading the ball into their opponents' goal, while the other team attempts to prevent them from doing so. Soccer is often used as a synonym for association football, as they are both essentially the same game.
1. My favorite hobby is playing soccer.
2. My brother plays on the local soccer team.
3. Soccer is the most popular sport in the world.
soccer is rather American variant of the word 'football.' Being in Europe, it's better to use a term 'football' to be understand. But in the US and Canada use 'soccer' since 'football' in these countries is considered as a different game.