DEFINITION
"A designation applied to a specified type of security such as common stock or mutual fund units. Companies that have more than one class of common stock usually identify a given class with alphabetic markers, such as "Class A" shares and "Class B" shares. Different share classes within the same entity typically confer different rights on their owners.
INVESTOPEDIA EXPLAINS
For example, a public company may offer two classes of common stock outstanding: Class A common stock and Class B common stock. This dual-class structure is typically decided on when a company first goes public and issues stock in the primary market.
For example, a private company that is undertaking an initial public offering (IPO) may choose to issue Class A shares to its new investors, while the original owners of the company receive Class B shares. In this case, the Class B shares would typically have enhanced voting rights. A dual-class structure such as this would be used if the original owners of the company wanted to sell the majority of their ownership stake in the firm, but still maintain majority voting rights.
As an investor, it's important to know what class of shares you are buying when you purchase common stock in a public company. "
( http://www.investopedia.com/terms/s/share_class.asp )
Real World Example From Google:
" Why bother? The new Class C shares have no voting rights. The Class A shares have one vote each, but collectively those votes are dwarfed by the 10-votes-per-share Class B shares. Those shares, which do not trade in the public market, are owned by Google insiders, who will also get Class C shares in the distribution.
As originally proposed by the company, the move would have made it easy for Google’s founders, Larry Page and Sergey Brin, and the chairman, Eric E. Schmidt, to cash in a large part of their holdings without giving up their voting control. But that ability has been limited after the company settled a class action suit filed by angry (Class A) shareholders, and reached agreements with the three top officials to limit their sales.
In essence, for every share of Class C they sell, they must also convert one Class B share into Class A. Presumably they will sell that share as well. So their voting rights will fall as they would have under the old structure, when they would have converted Class B shares into Class A shares before selling them.
But Google is expected to issue primarily Class C shares in the future, for acquisitions and in grants of share options. So the total number of votes will not be rising, and that will delay the day when the company’s leaders lose voting control of the company. Currently they own less than 16 percent of the company’s shares, and have 61 percent of the votes. "
( http://economix.blogs.nytimes.com/2014/04/02/the-many-classes-of-google-stock/?_r=0 )
