A thematic exhibit, also known as a topical exhibit, is one where the stamps and related philatelic material relates to a specific theme. To many, a collection of stamps is rather plain and boring, after all, you look up the country in a catalog and check them off as you get them. But to tell a story using stamps creates more interest. To tell the story of fabric, the history of the telephone, the history of certain countries or conflicts using stamps provides a way of sharing stamp collecting in a way that even a non-stamp collector can understand. And the best part is that no one can say you are doing it wrong, or not complete. You can collect things that interest you! The American Topical Association is the governing body in the US and conducts exhibits and provides checklists as starting points.