Not a problem (figured anyone who was interested enough to care already knew, but suppose I should not make those types of assumptions).
ACS = American Chemical Society
This is a huge non-profit organization that promotes chemistry and chemical education. Has something like 180,000+ members (chemists, in both industry and academia, as well as a few business and engineering folks who are involved in the industry) and is primarily funded by member dues and donations.
If you have any interest in chemistry, their web site has a lot of info on it:
www.acs.org