This book discusses the Uniform Commercial Code (U.C.C.) Articles 3, 4, and 4A in detail. It also explains to what extent provisions and interpretive cases decided prior to the promulgation of Article 4A and prior to the 1990 revision of Articles 3 and 4 are still useful, and why changes made were needed. It discusses issues not generally recognized and treated elsewhere, including the meaning of the new standard of good faith, the relation between "accountability" and "final payment," and consequences of radical truncation. In addition to the discussion of payment Articles in the Uniform Commercial Code, the book contains up to date discussion of other payment systems like credit and debit card systems, and other payment methods including prepaid cards, PayPal, mobile payments, and virtual currency transfers.