Introducing the Five Planes
The Five Planes method for user experience design is based on principles laid out by Jesse James Garrett in his seminal book, "The Elements of User Experience". His book explains that there are five explicit layers, or "planes" in UX design – Strategy, Scope, Structure, Skeleton, and Surface.
In short, each plane corresponds to questions which must be answered to solve a user experience problem.
- Strategy — What are we trying to accomplish with this project, and how will we know if we are successful?
- Scope — What are the features that will help us accomplish our strategic goals?
- Structure — How will the features fit together and interact?
- Skeleton — What are the interactive components from which we will build the features?
- Surface — What will the components look like when everything comes together?
For a successful UX design project, it is critical to treat each plane as a separate phase of design, and complete the phases in this specific order. If you read the questions above carefully, you'll see that it simply doesn't make any logical sense to tackle the five phases out of order. Attempting to do so is like trying to build a brick house before making the bricks.
The number one mistake I have seen in over a decade of UX design projects is tackling the higher, more detailed planes of UX design without having established a solid foundation in the planes below.
It's very common and normal for flaws in a lower plane to be revealed during the exploration of the next one. For example, in web design, during the wireframing process (part of the "Skeleton" plane), it's common to realize that the existing site map (part of the "Structure" plane) is difficult to navigate. This is a natural and healthy part of the iterative nature of user experience design.
But I've lost count of how many times I've seen a problem at the "Strategy" level only addressed during the "Surface" phase of design. This type of correction is extremely expensive and time consuming to repair. It's like realizing you built an apartment complex when you really needed a stadium—after you installed all the carpeting and painted the walls. A huge amount of work just needs to be thrown out and abandoned—and redone.
One dangerous misconception among project stakeholders is that the success of a design cannot truly be determined until the complete package is evaluated. In fact, the evolving practice of user experience design has developed a wide range of tools and processes to evaluate the success of a design during each of the five phases, or planes.