The bark from Birch is great for tinder.
Strip it down to thin strips to easily catch a spark.

However, if the bark is from a rotten, or damp tree. It may not be so easy.
Simply scrape up the top layer of dusty residue.
And throw a spark at it for a quick fire.

Pencil shavings are also a great source of dry tinder on a rainy day.
Who ever thought those Elementary school days of sharpening pencils would come in handy?