Starting a fire with some birch bark is a piece of cake. Even when the birchbark is still wet, it will light as if it was a dry piece of paper soaked in gasoline.
When you are on a hike, and you plan to make a fire later the day, it’s a good idea to collect already some tinder when you find it. Collecting upfront birch bark when you are in a birch tree forest might look stupid, but can you imagine your frustration when you want to lit your fire and you are in the middle of a pine tree woodland, or desert and the last birch tree was 20 km ago.
Always be prepared!