Okay, so imagine you have a toy and you lent it to a friend. But then, you found out that your friend made a copy of your toy and gave it to other friends without your permission. That's not okay, right?
Well, something similar happened with some music. A company called BMG Canada made some music and people were sharing it on the internet without permission. This is called piracy and it's illegal.
So, BMG Canada wanted to find out who was doing this and take legal action against them. They asked the court to give them the names and addresses of the people who were sharing their music online without permission.
The court agreed and said that the internet service provider (ISP) must give BMG Canada the names of the people who were sharing the music. These people were called "John Doe" because their names were not known at the time.
This was a big deal because it meant that people who were sharing music illegally online could be caught and punished. It also showed that companies like BMG Canada have the right to protect their music from being illegally shared.
So, the case of BMG Canada Inc. v. John Doe was really about protecting the rights of music creators and making sure that people who share music illegally could be held accountable.