We interact with more devices, more apps and more websites today than we've ever had and more show up each day. This makes, or should make, user experience designers more sought after than ever.
But designing an app or a site or anything else to be easily and intuitively usable by people, especially as the tools we use become increasingly abstract, is part science part art.
Still, there are some guiding principles that should at least give developers an idea of dos and don'ts when coming up with an interface or an action flow.
Those design principles, though, can be used for bad as much as for good. Harry Brignull, a user experience designer provides some insight into the ways websites or apps are designed to deliberately confuse and trick users, by relying on the same principles that should help developers create useful and clear apps.
By using what Brignull calls "dark patterns," many websites tend to obscure things like terms of service, hidden fees, email subscriptions and so on.
One example is "trick questions," i.e. questions designed to lead you into thinking you're doing the exact opposite of what you're actually doing. For example, a ticked checkmark may be used to indicate that you want to opt out of an email subscription, even though users would expect this to reflect an affirmative action, i.e. that you want to opt in.
Another "dark pattern" that is used to trick users is "forced continuity." For example, a site or app may allow you to get started and use some features for free and without any barriers, but as soon as you want to do something useful, you'd be presented with a barrier asking you to pay or sign up or something similar.
Good UX design practices indicate that users should be able to get to what they want with as fewer steps as possible.