payments

The 2025 GENIUS Act turned stablecoins from an unregulated experiment into a defined instrument with reserve rules, permitted issuers, monthly attestations, and a ban on paying holders yield. This lesson covers what the law requires, why the yield ban shapes the whole business model, and the risks the rules do not remove.

A stablecoin is a claim on an issuer that trades at a dollar because you can redeem it for a dollar. This lesson builds the mechanism: the mint-and-redeem arbitrage that enforces the peg, why reserve composition is the whole game, and what the USDC depeg and the Terra collapse each proved about how pegs actually break.

Scoped tokens and signed mandates solve authorization, not everything. This lesson covers the unsettled parts: who is liable when an agent buys wrong, why merchants and agents have opposing incentives, prompt injection as a new attack surface at checkout, agent-to-agent buying, and why the market forecasts disagree by an order of magnitude.

How do you let software spend your money without handing it your card? This lesson covers the mechanism behind agentic checkout: scoped single-use credentials like the Shared Payment Token, Google's AP2 intent and cart mandates as signed verifiable credentials, agent identification, and the guardrails that bound what an agent may buy.

You cannot understand agentic checkout without understanding checkout. This lesson builds the payment foundation: the five parties in every card transaction, the authorization-capture-clearing-settlement path, who really pays interchange, why card-not-present fraud shapes everything, and the tokenization idea that agent payments are built on.

Western phones hold a dozen apps for a dozen jobs. In China, one app is the messaging, the payments, the taxi, the bill, the government form, and the shop. Learn how the super-app model works, why mini-programs made bundling possible, why a market that skipped credit cards produced a different shape of internet, and what the design actually trades away.