x402
An open standard for internet-native payments that revives HTTP 402 Payment Required: the server responds 402, the client pays instantly with stablecoins and retries.
Plain English
A website can charge an agent a fraction of a cent per call with no accounts or API keys - the money rides on the HTTP status code.
Example
An agent hits a data API without a key, gets 402 plus payment instructions, settles $0.001 in stablecoin, retries, and receives the payload.
Why it matters
The machine-payable complement to mandate-style agent commerce protocols - the natural monetization primitive for agent-consumed APIs and pay-per-crawl content.