Architecture & practice·Design, structure and tradeoffs
another team reached into the field directly, and now you cannot rename it without breaking them.
Encapsulation
Also calledinformation hiding
Keeping a module's internals private so they stay changeable. The value is not secrecy — it is that whatever you expose becomes a contract you have to honour, and whatever you hide stays yours. Every leaked internal converts a future refactor from a local decision into a negotiation with everyone who reached in, which is the mechanism behind Hyrum's law.