Part 1. Understanding the Coming Problem
The primary goal of a mobile site or app is to deliver the right content in bite-sized chunks to the right person. Understanding the problem and exploring different options will establish a good foundation for understanding why a well-designed Mobile Search Interface is required and why it isn't enough to just have a search bar.
Content Navigation Patterns
Top Category Navigation Pattern
First, not having advanced navigation isn't always a problem. If the volume and variety of content available is small enough, a user can easily navigate a handful of top categories and quickly scroll through lists. Depending on a brief list of top categories is a time-honored approach that works well in many cases. However, if the volume and variety of content is larger than this "Top Category Navigation Pattern" can manage, you have frustrated users. Frustrated users mean people who are going to search for alternate sources to find the information needed. A retailer ought to panic at this idea. After all, if their customers can't find it, they won't buy it from your site - but they will go to a competitor's site. Within an enterprise, staff will look elsewhere for the information. That can have disastrous consequences as well.
Hierarchical Navigation Pattern
What is going on? As a site grows content is being grouped together into increasingly larger chunks. The user is now choking on what were once "bite-sized" chunks of content. In their frustration they look for other sources. The solution is to make content "bite-sized" again. A way to do this is to extend the "Top Category Navigation Pattern" (described above) and divide the Top Categories into sub-categories. This "Hierarchical Navigation Pattern" now presents content in bite-sized chunks again.
As a side bar, there is often confusion between talking about content navigation patterns and web widgets and techniques used to implement the patterns. For example, the Top Category Navigation and Hierarchical Navigation content patterns can be implemented using a variety of techniques and web widgets. A site might use Horizontal or Vertical Bars with a secondary Sidebar Navigation, Tabs Navigation, Breadcrumb Navigation, Tags Navigation, Fly-Out Menu and Drop-Down Menu Navigation. At the end of the day all these patterns are different ways of implementing the Top Category and Hierarchical Content Navigation Patterns.
For more on mobile widgets and techniques for implementing the Content Navigation Patterns, see the Android [Design] Patterns page . If you want to see similar patterns for web sites check out this page .
Where's Waldo or Stump the User Game
If you have ever designed a web site's navigation, you know what comes next. As the volume and variety of content continues to increase, you have to add a combination of top categories and sub-categories so you can present content in bite-sized chunks. At some point, the number of top categories and sub-categories get so large that your users are overwhelmed with all the choices they have to make and their frustration level increases and the site's success criteria decreases. One of the symptoms is that people have to jump through the hierarchy as riding a pogo stick. They have to navigate through a hierarchy to see if it contains the content they are seeking. If not, they try a different path until they either find what they are looking for or give up. If it weren't so frustrating, this could almost be a game of "Where's Waldo?" on your site. Usually users feel as if they are involuntary guests on the game show "Stump the user."
Guided Facet Navigation Pattern
To avoid the Navigational Pogo Game (aka Stump the User) sites turn to a different Navigation Design pattern: Guided Facet Navigation. Often encountered on retail sites, the pattern can be found on company intranet websites (but not as frequently since access to those sites require passwords). Instead of presenting users with a pre-determined navigational path (as required by Top Category and Hierarchical Navigation patterns), this pattern permits the user to choose a path that makes the most sense to them. This approach is often implemented using a search engine under the covers. An excellent example of this approach is found at Littleton Coin. Select one of the Top Categories along the top (such as Half Dollars) and the next page shows an example of the Guided Facet Navigation in action.
The Coming Problem for Mobile Devices
A design goal for any mobile app is to get the most relevant content to the user as quickly as possible. We just thought we had to be quick using a desktop web browser. With Mobile Apps and Browsers we have to be even more responsive. Many sites today are depending heavily on various implementations of the Top Navigation and Hierarchical Content Navigation patterns using a combination of toolbars, tabs and lists. Some have developed outstanding implementations. Two of my current favorites are the Amazon app store and the BBC new app - both for Android phones. I find that they are easy to navigate and get me to content quickly. However, they only present a sliver of what they will need or could present in the future. The BBC site is already there. There is far more available via the website than the mobile app. One explanation is that mobile users only want a subset of content rather than all the content.
I predict that this design approach of making only a subset of content accessible is going to be the heart the problem. Users are not going to be satisfied with only a subset of content available through their computer browsers. Adding more and more categories to maintain bite-sized chunks of content will not solve the problem.
The only approach that I see that will meet the needs of users without overwhelming them will be an implementation of the Guided Facet Navigation Pattern. However we won't be able to easily port the implementation approach taken by many retail sites today. Today users are presented with multiple facets from which to choose. There simply isn't enough screen real estate on a mobile phone to do that. A different design implementation and user interaction pattern will have to emerge to solve this problem - and that is the problem I will be discussing through this series: How to Build a Successful Mobile Search Interface.
You'll be able to follow this series through our monthly eNewsletter as well as via our blog The Tech Connection . It's designed to not only educate but to begin a dialogue related to the fulfilling the demand for effective mobile accessibility.
