Well, it was inevitable I’d have to talk about the difference between usability and accessibility at some point. This is a place where people often get confused, and while I haven’t seen the confusion be catastrophic, I can see where it absolutely could be one.
Why the Confusion:
Well, the term “accessibility” is sometimes used in terms meaning easy for the target demographic and related ones to adopt it, to use it and like it. “Inaccessible” is something you don’t want to be called, in that scenario. At the same time, “usability” has in some situations inverted its meaning to pertain to ease of use for people with special needs or concerns, or the like.
So, yeah. These two can be confusing, and the fact that they are a yin and yang of user experience, it’s a recipe for disaster that has mercifully not gone notably awry yet.
Let’s prevent that, and look at the differences between usability and accessibility properly. We’ll just look at one at a time, then conclude what the differences demonstrated really are.
Accessibility is mostly about facilitating people with special needs, but it goes beyond that to making it just generally easy to interact with and to read.
GUI is in and of itself an accessibility solution before it’s a usability one. It allows those who can’t work with walls of text and commands to actually use the complex systems in spite of that fact, among other things.
Accessibility does do things such as zooming for those with poor eyesight, voice commands for the blind, and onscreen keyboards and the like. These also serve to overcome device problems like touch screens lacking mice or keyboards, all of that fun stuff.
Finally, it also covers support by way of documentation, most of the time.
Usability is all about the design of a system making sense within context of its purpose, and to the people using it, so that repeated long term use is easy, efficient and instinctual over time.
This brings in sciences of flow navigation to get around sites or to go through menus to do processes in software. It brings in aesthetics and eye tracking and placement and layout and all of those lovely visual things as well.
Finally, it brings in learnability, which is how quickly people can learn the beginner and intermediate stuff that is doable in a design. Can they accomplish something real if small, after a few minutes of deductive button clicking?
Usability is harder to test, because a lot of it is about the relationship with humanity in general which a complex and abstract piece of software is aiming to establish.
Accessibility is mostly common sense, good technology (hopefully forever innovated upon), and very constant. There’s less fluffy human nature here, in spite of its demographic being a very specific set of humans. It’s because the problems here, if not solvable directly, can at least be accommodated by obvious solutions. The only direction to go here is in making sure it works damn well, and that you do all you can to continue to make it work better.
Now we see the distinction between usability and accessibility. However, we see that it’s all ok, because you can’t have one without the other, and you certainly can’t do with neither.