From Traderpedia

Definition: The first issue and sale of stock by a company to the public.

The actual process of selling the stock is generally done by an underwriter and often involves a road show and requires a prospectus, allowing the investor to do her/his due diligence. The sale is made at the offering price, then starts actual trade at the opening price.

Insiders are not allowed to sell their stock during the lockup period.

Also referred to as going public.

See also flipping.