# Idempotency

> The property that performing an operation twice produces the same result as once — the thing that makes retries safe in payment, order and automation systems.

Networks drop requests between 'sent' and 'confirmed'. If 'charge this card' is retried by a timeout, a user clicking twice, or a queue redelivering a message, a non-idempotent endpoint charges twice. The standard fix is an idempotency key: the client sends a unique token per logical operation and the server answers a repeat with the stored first result instead of performing it again.

Where it matters most is exactly where failure is most expensive — payment capture, order creation, webhook handlers, automation steps that send emails or move money. Designing the write paths to be idempotent turns 'retry on failure' from a risk into the normal way flaky infrastructure is survived.

## Related terms

- https://dfieldsolutions.com/en/glossary/ci-cd.md
- https://dfieldsolutions.com/en/glossary/static-generation.md
- https://dfieldsolutions.com/en/glossary/n8n.md

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Source: https://dfieldsolutions.com/en/glossary/idempotency
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