Preferred Stock
Preferred stock is represents an ownership interest that has a higher claim on company income and assets than common stock. Preferred shares generally have a quarterly dividend that has to be paid before dividends to common shareholders. The shares usually do not carry voting rights when issued to the public at large, however in the context of venture agreements, Angels and VC will generally bargain for voting rights.
The details of each preferred stock depend on the issue and can be one of the most contentious issues when funding a private company or startup.