1. GAAP and the Conceptual Framework
GAAP is the common set of accounting standards and principles issued by the FASB so that U.S. companies' financial statements are comparable, reliable, and consistently prepared.
Key assumptions/principles: economic entity, going concern, monetary unit, periodicity, historical cost, revenue recognition, expense recognition (matching), full disclosure; fundamental qualities: relevance and faithful representation; enhancing qualities: comparability, verifiability, timeliness, understandability. FASB issues GAAP through the Accounting Standards Codification (ASC); the SEC holds statutory authority over public-company reporting; the IASB issues IFRS internationally.
GAAP (FASB, U.S., historical-cost/rules-based) vs.\ IFRS (IASB, international, more principles-based, permits some asset revaluation).
Assuming "conservatism" means understating everything --- it only applies when genuine uncertainty exists: recognize losses/liabilities as soon as probable, but never anticipate revenues/gains early.
FASB writes GAAP $arrow$ codified in the ASC $arrow$ SEC enforces it for public companies.