GAAP is built from three kinds of rules. See which kind each one is.
makes one company's statements comparable to another's. In the United States, the sets it, under authority from the . Most other countries use , set by the .
The keeps FastForward's books separate from its owner's personal finances. The assumes the business will keep operating, not liquidate tomorrow.
The is the reasoning underneath GAAP — why these principles exist, not just what they say. It is what standard-setters use when a new kind of transaction does not fit an existing rule.