GAAP (Generally Accepted Accounting Principles)= Body of authoritative accounting regulations used in the United States and adopted by the Securities and Exchange Commission (SEC).
FASB (Financial Accounting Standards Board)= Regulatory wing under the SEC that is responsible for establishing GAAP.
ASC (Accounting Standards Codification)= The codification system for organizing GAAP rules. This replaced the former accounting standards (SFAS, FIN, etc.)
GAAP, FASB, FAS, ASC...etc