This guide covers electronic signatures and online contract formation end to end, for the lawyer advising a business, the litigator attacking or defending an agreement, and the consumer trying to understand what they clicked. Part 1 covers what the federal statute and the uniform state act actually do, which is narrower than assumed, and the exclusions that trap careless practitioners. Part 2 covers the consumer consent procedure required when an electronic record substitutes for a statutory writing. Part 3 covers formation: the clickwrap taxonomy, the notice and assent standard, and the factors courts apply. Part 4 covers attribution, records, and the audit trail that makes an agreement provable years later. Part 5 covers unilateral modification. Part 6 covers arbitration clauses and why formation is the whole battlefield. Part 7 covers the regulatory overlay: dark patterns, negative option billing, children, and commercial email. Part 8 covers signature platforms and remote notarization, and Part 9 covers litigation on both sides.