An Initial Public Offering (IPO) is the moment a private company first sells its stock to the public on a securities exchange. The mechanism dates to the Dutch East India Company in 1602 and has not changed in substance since: the company picks an underwriter (an investment bank), drafts a prospectus disclosing its business, financials, and risks, files it with the SEC, and — once cleared — markets the offering to institutional investors during a roadshow before the bank sets a final per-share price and the shares list.