GAAP(Generally accepted accounting principles) are used to prepare and report financial statements. GAAP are the principles for accounting and financial statements

The ultimate goal of GAAP is to ensure a company's financial statements are complete, consistent, and comparable. This makes it easier for investors to analyze and extract useful information from the company's financial statements, including trend data over a period of time.

 For example, GAAP stipulates how to file income statements, what financial periods to include, and how to report cash flow. Showing  their revenues before any kind of financial statement.