This has to do with the difference between authorized shares and issued shares. The Gold Standards setup for a Technology Startup is to authorize 10,000,000 shares of common stock for the formation of a startup. However, for a single founder corporation, from these 10,000,000 shares, we only issue 1 million shares to the Founder.
The other 9,000,000 (9 Million) are reserved in the treasury for a possible future co-foudner, future employees, advisors, and sometimes for early investors.
However, a Corporation is controlled by the ISSUED shares, not the AUTHORIZED shares. So this means, if you own One Million of the One Million issued shares, then you have 100% control over the company.