Flat versus Deep – Choosing Between Website Hierarchies
When it comes to website structure, web pages can be arranged in two ways: in either a flat or a deep hierarchy. Having some sort of system is crucial to organizing content, and arranging them into groups, and then into subgroups, is what’s known as a hierarchy of content. It’s a structure that’s not all too different from what know in organizations, family trees, and even flora and fauna.
So why should you care about content hierarchy?
The manner in which your content is structured can have a major impact on how your website works for users, so it pays to make the right decisions. There are plenty of factors and nuances behind it, so the best way to understand the differences between a flat or deep hierarchy is to give you a bird’s eye view of the structure.
Consider the image below taken from web usability experts the Nielsen Norman Group
On the left side is a flat hierarchy, which as the name describes, is broad and short with 8 categories spread thinly. On the right side is a deep hierarchy, which as you can see, has only 4 categories and 8 subcategories, but cascades down into multiple levels and even more subcategories, giving it a tall and narrow appearance.
Both types of content structures have an equal amount of information, arranged into two different but equally understandable hierarchies. However, a user’s experience when going through these structures will be completely different.
Pros and Cons
The average web user will probably never think of these structures, let alone see it in this kind of visualization. Nonetheless, they will feel it.
Web content is easier to find when it’s not buried under multiple layers of categories, that means deep hierarchies have the short end of the stick.
Likewise, specific categories that don’t overlap against one another are easy to understand, but that doesn’t necessarily mean that flat hierarchies are superior. True, deep hierarchies have tendency to be more generic and confusing due to having fewer categories on each layer.