"A wise man once said..." Ever wonder who said that famous quotation? Then you're curious about its attribution. An attribution identifies a source or cause of something — in this case, the person who first said the quote.
Attribution often involves identifying the author or source of written material or a work of art. If you want to prove that painting you found in your basement is a van Gogh, you'd produce evidence to ensure proper attribution. The word can be used more generally to indicate the source of anything, whether it's a bombing, climate change, or success. For example, attribution of your success might be hard work and the support of family and friends.