When people make movies, sometimes they forget about them or lose them. These movies are called "orphan films". They're called "orphans" because no one is taking care of them or looking after them.
Just like when you leave your toy at the park and forget about it, these movies are left behind and nobody knows where they are or what to do with them. Sometimes they stay lost forever, but other times people find them and take care of them.
It's important to take care of these orphan films because they can teach us a lot about history and how people used to make movies. Just like you can learn from old pictures of your grandparents or their stories, we can learn from orphan films too.