# Robustness

Every API implementation and API consumer **MUST** follow Postel's law:

> *Be conservative in what you send, be liberal in what you accept.*
>
> *–* [*John Postel*](https://en.wikipedia.org/wiki/Robustness_principle)

That is, send the necessary minimum and be as tolerant as possible while consuming another service ([tolerant reader](https://martinfowler.com/bliki/TolerantReader.html)).