Various "rules" guide how a company's financial statements should be prepared so that

different companies can be compared and a company $($or companies$)$ can be compared

across time. These are referred to as

Financial Accounting Standards Board $($FASB$)$

Generally Accepted Accounting Principles $($GAAP$)$

International Accounting Standards Board $($IASB$)$

Securities and Exchange Commission $($SEC$)$