This January 13, 2003 NASD (and now updated on the FINRA site) investor alert describes Class A, B, and C mutual funds shares and lists some considerations in the choice of classes. (Note that The Skilled Investor believes that you should understand the full lifetime costs of paying any form of sales load. Investment sales loads can be an excessively costly way to pay for "advice.")
On its "About" homepage, FINRA describes itself as:
"The Financial Industry Regulatory Authority (FINRA) is the largest independent regulator for all securities firms doing business in the United States. FINRA's mission is to protect America's investors by making sure the securities industry operates fairly and honestly. All told, FINRA oversees about 4,380 brokerage firms, about 162,845 branch offices and approximately 629,640 registered securities representatives. FINRA has approximately 3,200 employees and operates from Washington, DC, and New York, NY, with 20 regional offices around the country."