A private company becomes a public company in a process called an initial public offering (IPO). Historically, only private companies with a strong track record of years of growth have considered themselves ready to take this significant step. The IPO has pros and cons that include exchanging a host of high regulatory costs for the benefits of significant capital. After a company "IPOs" or "goes public," investors and the general public can buy stock, and existing shareholders can sell their stock far more easily than when the company was private.
Stock options, RSUs, job offers, and taxes—a detailed reference, including hundreds of resources, explained from the ground up and made to be improved over time.