There is a difference between uncertificated and certificated shares, and stock certificates are not the same thing as stock. See the Delaware General Corporation Law § 151(f): "If any corporation shall be authorized to issue more than 1 class of stock or more than 1 series of any class, the powers, designations, preferences and relative, participating, optional, or other special rights of each class of stock or series thereof and the qualifications, limitations or restrictions of such preferences and/or rights shall be set forth in full or summarized on the face or back of the certificate which the corporation shall issue to represent such class or series of stock...Except as otherwise expressly provided by law, the rights and obligations of the holders of uncertificated stock and the rights and obligations of the holders of certificates representing stock of the same class and series shall be identical." Some shares are certificated, meaning that their owners possess physical stock certificates, and some are uncertificated. Thus, a "stock certificate" is a physical item, and it's not the same thing as a "stock." HTH.
http://delcode.delaware.gov/title8/c001/sc05/index.shtml
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