Book Building is defined as the process through which an underwriter - typically an investment bank, attempts to determine the IPO offering price. It is also known as the process of price discovery, which enables underwriters to understand the demand for shares of the company before arriving at an issue price. The underwriter essentially builds a book by inviting various institutional investors like fund managers and others to submit their bids for the number of shares they would be willing to purchase and share prices they would be willing to pay if they purchased the company's shares on a public platform. Book building is thus the de facto mechanism by which companies price their IPO in share market. All major stock exchanges worldwide recommend book building as the most efficient method to price securities.