What is usability and why does it matter?

19th September 2019
Posted by in Brain Bites: 2 Minute Insights

The word usability gets used a lot in UX circles but what does it actually mean? I am going to give you the official definition and then explain it because it can be a bit of a head-scratcher at first.

The ISO 9241-11 definition of usability is: “the extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.”

What on earth does that mean? Well, to make sense of it, let’s break the definition into parts and look at them in detail:

  1. “the extent to which a system, product or service…” tells us that usability falls on a scale (some designs will be more usable than others) and that this definition has an incredibly wide scope – it can be applied to almost anything that serves a purpose.
  2. “…can be used by specified users…” suggests that we need to know who our users are – we need to understand them by researching their needs and behaviours, rather than guessing at a one-size-fits-all solution that doesn’t actually work well for anyone.
  3. “…to achieve specified goals…” examines whether the users who interact with the system, product or service can achieve what they intend to do.
  4. “…with effectiveness, efficiency and satisfaction” looks at three things: Can what they want to achieve be done? Can it be done quickly and easily? How do they feel about it?
  5. “…in a specified context of use” ensures the users’ physical and social environment is taken into account. For example, an underwater camera may work well on land but to understand how usable it is you need to test it in water!

To ensure a system, product or service is as usable as possible, all of these elements have to be considered. Understandably you might think, “That sounds like a lot of work…how much does usability matter anyway?” Well, there’s a carrot and stick answer to this.

Let’s start with the stick. It is now common practice for companies to focus on usability. 10 years ago, the usability of a system, product or service would have been a differentiator; now it’s a hygiene factor. Users now expect websites to allow them to do what they want, quickly and easily, and if your website doesn’t do that, users have a wealth of other places they can visit instead. So, if you want your website to be around in a year’s time, you’d better make it usable; if it’s not, your customers will quickly leave.

And the carrot? Making your design usable creates a virtuous circle for both your customers and your business. Your customers will achieve their goals quickly and efficiently. This will leave them happy which improves their perception of your brand and the likelihood of repeated visits and recommendations to others. In short, you have created a great ‘user experience’. Your business will benefit from an improved conversion rate or, in the context of an intranet site, increased employee productivity.

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We are psychologists, interaction and design experts, researchers, usability specialists. We cover Web, software, mobile, print, service design and more.
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