Defection is when someone who is part of a group decides to leave and join the other side or become independent. It's kind of like when you're playing a game with your friends, but one of them decides to switch teams or play by themselves instead. Sometimes people might defect because they don't agree with what their group is doing or they want to do something different. Other times, they might have been offered something better or feel like they will benefit more by switching sides. Defection can happen in all sorts of situations, like sports teams, political parties, and even families. But just like in a game or in life, when someone defects, it can have consequences and affect the people they were once working with.