Knowledge spillover is a way of thinking about how knowledge and ideas travel. Imagine that every time you learn something new, it 'spills out' and spreads to others who didn't learn it in the same way. This can happen in a variety of ways, such as when you tell someone about something you've learned or when you share what you know on the internet. When knowledge spreads like this, it can lead to new ideas and discoveries that wouldn't have happened otherwise.