Usability measures how easily a person achieves their goal with a product: its effectiveness (getting there), its efficiency (without wasted effort), and the sheer satisfaction they derive from it.
The standard definition is formal: ISO 9241 identifies these three key criteria, and Jakob Nielsen made them wonderfully actionable with his ten heuristics (1994) – system status visibility, consistency, error prevention. Measuring usability is all about observing users complete tasks and identifying where the friction lies.
Yet, usability has a blind spot, as Nielsen himself points out: a product can be perfectly usable and utterly useless. Ease of use answers "is it simple to use?"; it doesn't answer "does it actually serve a purpose?". You can endlessly polish a tool that nobody needs. Utility (solving the right problem) and usability (the right execution) are two distinct questions, and the latter can never rescue the former.
Hence, our golden order of priorities: first, ensure we are solving a genuine problem, and only then make it effortless. An exquisite design for something useless is still useless, just beautifully packaged!
Our approach: we test usability through real-world observation, because friction points can't be guessed – they must be seen. But we never start there: first, we capture the right problem (utility), then we craft the flow (usability). Useful and easy, in that exact order!
What's also in play: utility, UX, user testing, ergonomics, and cognitive load.
References: ISO 9241 standard (effectiveness, efficiency, satisfaction); J. Nielsen, ten usability heuristics (1994).
Rémi
Gréau
Director of Design
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