What is a stock certificate?

A stock certificate is prima facie evidence that the holder is a shareholder of the corporation,[1] but the possession of the certificate is not the sole determining factor of one’s stock ownership. A certificate of stock is merely:
x x x the paper representative or tangible evidence of the stock itself and of the various interests therein. The certificate is not stock in the corporation but is merely evidence of the holder's interest and status in the corporation, his ownership of the share represented thereby, but is not in law the equivalent of such ownership. It expresses the contract between the corporation and the stockholder, but it is not essential to the existence of a share in stock or the creation of the relation of shareholder to the corporation.[2] (Emphasis supplied.)
[1] Lao v. Lao, G.R. No. 170585, October 6, 2008.

[2] Tan v. Securities and Exchange Commission, G.R. No. 95696, March 3, 1992.