Even though the International Organization for Standardization provides a formal definition of user experience (UX) and explains the difference between usability and UX (alongside dozens of similar articles on the topic), there is still plenty to read and write about the two terms—and plenty of differing opinions.
The bottom line is that usability is part of the user experience.
Allow me to explain this by looking at user-facing quality as a pyramid.
Imagine you've just downloaded a video presentation in the newest video format, but your tablet cannot play it. It means your plans to watch it on the plane will fail, so you need a video converter to save the video in a format playable on your tablet before you board. You may start looking for one on Google, making sure the converters support the two formats you need: the one your video presentation is encoded in, and the one that your tablet can reproduce.
If you find software that can do the job, that is utility—the base of the pyramid. (If the software can’t even do the job, then no other element of user experience matters, does it?) Sometimes software lacks utility: The requirements are out of date or wrong, or the product just isn’t the right fit.
Now, let's imagine you've found a video converter with all the required functionality, so you're technically able to convert the file. Does that mean this is everything you need from the product? No. Now you need to successfully install the program, learn how to use it, and finish your task within a short timeframe. How well you can do that depends on usability.
Usability is the next level of the pyramid. To better understand what it entails, I’ll split the concept into four elements: adoptability, learnability, efficiency, and transparency.
Adoptability answers questions such as:
- How easy is it to start using the product?
- How easy is it for users to find, buy, download, install and actually access the functionality?
Many of us have found software that takes hours to download, has an arcane web storefront, or requires us to start something else in order to begin using it. All these setbacks mean fewer users actually getting to the product.
The most famous example is the $300 million button. A large e-commerce site required its users to register in order to finish a purchase. The company thought its users wouldn’t mind signing up, but as it turned out, many users instead decided not to register and left the site. After removing just that registration button, the company’s revenue went up $300 million within the first year!
Coming back to our imaginary video converter, the first challenge is to successfully download and install it.
If the one you found looks like what you need, you'll probably click a "Buy" button. But, oops ... In order to continue you have to complete a three-screen form, and there is no guarantee even that will bring you to the end of the process. Some users simply won’t do that, which means low adoptability.
When you've finally installed the program and run it for the first time, you have a new challenge: You have to quickly learn how to use it.
Learnability answers questions like:
- How easy is it for users to accomplish their tasks the first time they use a new product?
- How easy is it to find a needed functionality?
- Does a product work exactly as users might expect it to work?
- Does the product reasonably comply with existing standards?
- Does a user need any assistance to effectively work with the product?
Even if a product is efficient, if the users need to expend more effort than they originally expected in order to learn how to use it properly, they will select an alternative product.
In most cases, a user already has an idea, or even a "mental model," of how the product should work. Using the previous example of a video converter, a user would probably think: "A video converter should have a button or a menu item to open a video file. After the file is opened, I'll need another button or a menu item to convert it, choosing an appropriate output format from a list of options." If the approach to converting files used in the actual product is different, a user might feel frustrated by needing additional effort to learn the real functions. If the learning process takes too long, a user may start thinking of finding a different product.
If your video converter works exactly as you expected and you've successfully learned how to convert your file to a needed format, you're now an "engaged user" with a new requirement: The product should not just work—it should work quickly.
Efficiency, the third usability aspect, answers the following questions:
- How efficient is the interaction with a product?
- How much time and effort does a user need to finish the task?
- Does the product respond within a reasonable time?
- Does the product protect users from making errors? If users still make some mistakes, how easy is it for them to recover?
A simple example of efficiency is batching up a directory or set of files. If the application forces users to select one file at a time, but a use case is hundreds of files, the users might not exactly become raving fans.
Even if a program works effectively, there is no guarantee that it will also work reliably.
As the fourth usability aspect, transparency answers questions such as:
- How clear is the product’s state and behavior to users? How likely are the users to misinterpret it?
- How reliable is the product from a user’s point of view?
- Does the product protect users from destructive actions or data loss?
What if your video converter was not able to convert a file due to lack of free space, but it didn’t warn you about it? If the file is clipped, you may easily not notice until you actually started to play it. What if the program doesn’t ask about the output file name, and by default it overwrites your original file? This is also probably not something you’d expect.
Any of these examples would make a video converter unreliable or undesirable, and that could force a user to look for a different product.
Some authors call this attribute desirability, but I prefer the word identity. At this level of the pyramid, users start to think of the application as “theirs.”
As a quality attribute, identity answers the following questions:
- How aesthetically pleasing is the product's design?
- What emotions does the product evoke?
- Would users say using the product is "fun"?
- Is the product meaningful for its users?
- Does the product look credible and trustworthy?
This attribute additionally covers the issues related to the personal identity of a user: What does my ownership or use of this product say about me?
The product may be useful and usable, but if for some reason it is not attractive, users will not use it. According to Nielsen Norman Group's research, users prefer the design with the highest usability metrics 70 percent of the time—but not 100 percent.
When users like a product, they may overlook its utility and usability flaws. As design strategist Don Norman facetiously observed, "Aesthetics matter: attractive things work better." And it's not only about software and hardware; people tend to like stunning, though expensive and impractical, supercars and stylish, minimalistic watches without numbers.
Taking mobile phones as a new example, would you exchange your iPhone or Android gadget for a phone that is more powerful but looks like a brick, with a boring black and white interface? Probably not.
Conversely, what if the program has an obnoxiously bright pink design, or starts with an annoying animation, or each click is accompanied by a loud sound that can't be disabled? Or the program might have a blinking ad that promotes controversial content, or maybe your firewall took a dislike to it, and now regular warnings appear about suspicious activity. That could become a serious issue for a user.
I have to stress, though, that identity is a very subjective and a hard-to-measure attribute. After all, what is a “unit of aesthetics” or a “unit of fun”?
Finally: User Experience
User experience covers all the quality attributes discussed: utility, usability, and identity—in other words, the whole pyramid. Additionally, it covers the anticipated and digested use of the product, as well as all related online and offline services.
The anticipated use is an expectation about how the product behaves. For example, for many iPhone users, their UX began when they watched the first advertisement.
The digested use is a reflection of the experience of actual usage, as well as emotions and reactions the user had. It's close to an after taste—when you finally sit in the airplane, watch the video, and recollect how much time and effort you spent to convert it.
So, usability is one of the quality attributes of a product, indicating how easy it is for users to use the product and the efficiency of their interaction. User experience is a broader concept that includes usability as well as utility and identity. It also covers the anticipated and digested use of the product and all related online and offline services.
UX is influenced by three key factors: a system, a user, and a context of use. Only the system can be controlled, so it is your job to ensure that you provide the best system possible to engage and retain users. You can't design a user experience, but you can design for a user experience.