Laws of UX

Chapter 5. Postel’s Law

Be conservative in what you do, be liberal in what you accept from others.

Key Takeaways

• Be empathetic to, flexible about, and tolerant of any of the various actions the user could take or any input they might provide.

• Anticipate virtually anything in terms of input, access, and capability while providing a reliable and accessible interface.

• The more we can anticipate and plan for in design, the more resilient the design will be.

• Accept variable input from users, translating that input to meet your requirements, defining boundaries for input, and providing clear feedback to the user.

Overview

Designing good user experiences means designing good human experiences. People don’t behave like machines: we are sometimes inconsistent, frequently distracted, occasionally error-prone, and usually driven by emotion. We expect the products and services we interact with to intuitively understand us and be forgiving. We expect to feel in control at all times, and we’re generally annoyed when asked to provide more information than is necessary. At the same time, the devices and software we use vary greatly in terms of feature support, capabilities, and form factors. To be capable of meeting users’ expectations, the products and services designers build must be robust and adaptable. Postel’s law, also known as the robustness principle, gives us a guiding ...