Share classes represent different ways fund companies package their product. The basic product is the “strategy”— which is what you probably think of as “the fund.” For example, American Funds Growth Fund of America is a strategy. American Fund Growth Fund of America has many share classes that are represented by unique tickers; for instance, the ticker for the A-share class of the strategy is AGTHX; a no-load share class is GFAFX, and one of the share classes designed for use in retirement plans is RGAGX.