Alcoholics Anonymous has long been known for the anonymity of its members. But there are two key figures in AA's history whose names are well known.

One is co-founder Bill Wilson, known as "Bill W." Beginning in the 1930s, Wilson and Dr. Bob Smith began helping other alcoholics in order to maintain their own sobriety.

Wilson's simple grave in Vermont makes no mention of his work. That doesn't stop people from visiting it, especially on this annual Bill W. Day.