This is a document I wrote while at Desiring God to summarize our usability philosophy in about 15 principles.

Web design is about far more than the graphic look of a page. It pertains to how the site is organized, how the information is structured on a page, and how the user interacts with the site. Good design creates satisfied users; bad design means that your site will not be utilized to even half of its potential.

What follows are the core principles for designing an effective website.

1. Usability: Don’t Make Them Think

Sites that are hard to use, don’t get used much. Sites that are harder to use than they have to be, get used less than they should be. The Web is a mass medium. If your website is hard to use, you are failing to capitalize on the medium of the Web—not to mention making a bad impression and undermining user confidence in your organization.

Ease of use is our core principle, and therefore it is worth some elaboration.

What is usability?

“Usability is the extent to which a site can be used by a specified group of users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use” (Powell, Web Design: The Complete Reference, 50).

As Steve Krug has so simply shown in his book Don’t Make Me Think: A Common Sense Approach to Web Usability, one simple sentence sums up the definition of usability: A usable website is one that doesn’t make people think. In other words, it doesn’t raise question marks in people’s minds about how to do this or that, how to get here are there, or how to respond to the information on the page. They see the page, and know what they need to do, and how to do it.

This principle is “the ultimate tie-breaker in deciding whether something works or doesn’t in a Web design” (Krug, Don’t Make Me Think, 11). It is the very definition of what a usable site is.

Krug fills out the meaning of this principle more fully:

It means that as far as is humanly possible, when I look at a Web page it should be self-evident. Obvious. Self-explanatory.

I should be able to ‘get it’—what it is and how to use it—without expending any effort thinking about it.

Just how self-evident are we talking about?

Well, self-evident enough, for instance, that your next door neighbor, who has no interest in the subject of your site and who barely knows how to use the Back button, could like at your site’s Home page and say, ‘Oh, it’s a _____.” (With any luck, she’ll say, ‘Oh, it’s a _____. Neat.” But that’s another subject.)

You could also take another angle on defining usability, which is complementary to “don’t make me think” but not nearly as memorable or basic. 5 things determine a site’s usability:

1. Learnability
2. Remberability
3. Efficiency of use.
4. Reliability in use.
5. User satisfaction.

But it is much easier to just remember one thing: Don’t make people think.

What are the benefits of usability?

If your site is not usable, it adds to people’s cognitive workload: “When we’re using the Web every question mark adds to our cognitive workload, distracting our attention from the task at hand. The distractions may be slight but they add up, and sometimes it doesn’t take much to throw us” (Krug, 15). Add to people’s cognitive workload can have many ill effects, while lessening their cognitive workload can have many good effects.

1. Good usability makes everything seem better. “Making pages self-evident is like having good lighting in a store: It just makes everything seem better. Using a site that doesn’t make us think about unimportant things feels effortless, whereas puzzling over things that don’t matter to us tends to sap our energy and enthusiasm—and time” (Krug, 19).
2. There is a better chance that users will understand what they’re looking for.
3. There is a better chance they’ll understand the full range of what your site offers.
4. There is a better chance of steering them to the parts of the site you want them to see.
5. Users will feel smarter and more in control, which will bring them back
6. Users will have more confidence in your organization.
7. Good usability creates a good impression.

How do you know if a site is “usable”?

Not by talking about what you “like” or “don’t like.” Rather, you determine if it is usable by watching real people use your site, and seeing what creates obstacles (makes them think) and what works simply (doesn’t make them think). This is why user testing plays a key role in our Web design process.

But before the stage of user testing, you don’t have to shoot in the dark. There are several principles which are implied by the principle of usability—implied not only in terms of being logically correlated, but in terms of being shown to accord with usability in actual user research.

The remaining principles outlined below are just of this sort—they are all implied by the overarching principle of usability, and hence ultimately serve to flesh out more fully what usability means.

2. Use the smallest effective difference

When attention needs to be called to something or a distinction needs to be made between two different layers of information, it ought to be done with the smallest difference that effectively makes the distinction known. Otherwise, you are simply adding noise to the page.

For example, in a chart of baseball stats, thick, black gridlines simply distract from the information. They are one more thing to ignore. The gridlines should be soft and undistracting.

3. Eliminate the unnecessary

It is from this principle that the above principle of the smallest effective difference derives. Things that are unnecessary distract. In our homes, we call such things trash, and take them out to curb for the garbage truck every week. How do you determine if something is necessary? By considering your goal. If something advances the fulfillment of the goal for your site, or for a particular page on your site, it is relevant. Probably—as long as it doesn’t have side effects that are worth less than its benefits. If it does not advance the goal, it should be removed.

4. Group like with like

The basic principle for organizing anything is to group like things together. Crucial to good groupings is to define the basic similarity or quality that is serving as your organizing principle.

5. Arrange for access

Put simply, you put things where they will be used. On a checkout page, for example, this means you put the “You will have a chance to review your order before submitting it” sentence right next to the “continue” button on the payment screen, because it’s when deciding whether to click the button to go to the next step that that concern arises in the user’s mind.

Likewise, this principle means that you integrate content whenever possible. For example, on the page where people are able to sign up for an account, you wouldn’t want just have a link that says “benefits of registration,” requiring the person to click before they see any benefits. Rather, you would state the benefits right there. If you have more benefits than will fit, you state a few benefits right there, and have a link to the full list.

6. Provide good orientation

The most common user question is “where am I?” It is absolutely essential to orient your users. First, this is done by providing clear navigation that makes it obvious where they are—and how to get somewhere else. “Clear, well-thought-out navigation is one of the best opportunities a site has to create a good impression” (Krug, 60). Second, this is done by using good page titles—on every page.

7. Be consistent

Consistency means that if you do something a certain way in one spot, then it should be done the same way everywhere (unless there is a compelling reason otherwise—and the desire to “spice things up” and “make them interesting” doesn’t count).

This is illustrated very clearly in navigation. For example, as Krug points out, if a navigation label says “Lug Nuts” but takes you to a page called “Nuts,” you are making your user think—they have to ask the question of why the name of the page is different than what they clicked. Is it because they were taken to the wrong page? Or is it because “lug nuts” is considered a type of “nut?” Probably the later, but why make them as the question? The more different the name is, the worse you make it (for example, if the link was “Lug Nuts” and the page was “Spare Parts”). When I see sites do this sort of thing, it communicates two things: (1) They don’t care; (2) they are lazy.

8. Follow Web conventions

If you follow Web conventions (like global navigation goes across the top; local navigation goes underneath it or on the left; buttons are used when clicking initiates a task [like add to cart]; periods go at the end of sentences; etc.), then people will know how to use your site because they know how to use other sites.

If you don’t follow Web conventions, people will have to relearn your site. And it is hard to think of anything else that would make your users have to think more.

Many sites choose not to follow conventions because they want to be “unique.” If you want to be unique in this way, you need to weigh the cost—will it be worth what we lose by making our users think so hard? Usually, the sites make the wrong choice when they opt for the trendy over the conventional. Further, within the context of standard conventions, there is an infinite number of ways to be unique. Consider a book. Table of contents, page numbers, chapters, text that goes from left to right, and such are standard fare—conventions. But there are still plenty of ways to make your book stand out, without choosing to jettison page numbers or left to right text.

Be unique. Just don’t do it in the wrong way.

9. Don’t try to be fancy, and try not to use Flash

One trend that many sites give into is to use Flash. The typical thinking is that it looks neat and gives a multi-media feel to the site. But unless you are an entertainment site, where users come to be entertained, Flash will usually distract from the users’ goal, and therefore get in their way.

A related horror is that of splash pages—those nifty pages you encounter before the site’s home page which give you an animated intro to the site. These especially interfere with user goals. When you go to the Chipotle website to see the menu, for many people sitting through an animated scene of a talking burrito is just a frustrating delay in the pursuit of their goal. As someone has once said, the two most embarrassing words in Web design are: “Skip intro.”

10. Weave things in, don’t just start a new section

When a new idea comes up, the tendency is to want to create a “section” on the website for it. Sometimes that is warranted. But sometimes, after 10 such ideas, you end up with an incoherent site structure. Far better, when possible, to weave things in, integrating with existing content.

11. Make obvious what is clickable

The Web is pretty much about clicking. It’s how you get from one page to the next. Therefore, each page needs to make obvious what is clickable. You shouldn’t rely on users having to roll their mouse over something to see if it’s clickable (that makes them think).

It should also be clear where each link will go, so users do not need to proceed by trial and error.

12. Do not structure the site around the organizational hierarchy

Users don’t care about an organizations internal org chart. The site needs to be structured according to the content, and how users would think about the content.

13. Be concise

People don’t read Web pages, they scan them. Therefore write succinctly, and eliminate happy talk (the “welcome to this section of our site…” type of thing). Here are some basic guidelines for writing for the Web:

1. Be succinct.
2. Write for scannability:
   1. Do not use long blocks of text.
   2. Do use short paragraphs.
   3. Do use sub-headings.
   4. Do use bulleted-lists.
3. Use inverted pyramid principle, as possible.
4. One idea per paragraph, with topic sentences.
5. Omit needless words.
6. Minimize happy talk (such as “welcome to this page…”).
7. Minimize instructions.
8. Info that is only of interest to a minority of readers should be made available through a link.
9. Use consistent capitalization and other style standards so that all usage is consistent.
10. Headlines:
    1. Should make sense even when the content is not right there under it.
    2. Should be clear and plain. Nothing cute.
    3. Should not be mere teasers. We should provide clear expectations.
    4. Should make the first word be info-carrying.

14. Don’t use cute or clever names for labels and links

No clever or cute label names should be used—people do not click on such links because they don’t know where they go.

Good labels are also consistent in these aspects:

1. Style: punctuation, etc.
2. Presentation: fonts, sizes, colors, white space
3. Syntax: no mixing of verb-based and noun-based. Use a single syntactical approach.
4. Granularity: all roughly equal in their specificity.

 15. Focus on content

Ultimately, the interest and engagement level created by a site is a function of it’s content. Usability keeps the site from being an obstacle to its own content, so that the content can shine. “Original, quality content is the most valuable commodity of the Web. Users look for useful content and consume it voraciously once they find it” (Powell, 13).

This is not an exhaustive list of the principles we seek to follow in designing for the Web. For a more complete list, see our document Usability and Design Principles for DesiringGod.org.

Categorizing essentially consists of grouping like items together (classification) and assigning good labels to those groups (labeling). If it is going to be effective, categorizing needs to be done according to sound principles. Alternatively, if something is not categorized well, it is probably not understood well and will likely not communicate well.

This document outlines the key principles for how to categorize. It provides the framework to follow when grouping our content by topic (see the Topic Listing document for a list of our current topics and The Nature of Our Topic Index for a summary of the purposes and policies for our topic index) or into various other category groupings (such as those defined in the document Desiring God Classification Schemes).

Why Categorizing Matters

Categorization matters for several reasons, especially on websites. First, good categorization reveals site content. For example, thousands of site pages become more manageable when “summarized” by 8 primary categories. Second, good categorization reveals the structure of the content. Categories provide a framework for understanding and aid exploration because similar things are grouped together. Hence, presenting people with a logical set of categories that reveals the contours of the content is actually a form of teaching—a way of informing people how to think about and interpret what they find and associate it with other content.

Third, good categorization enables ease of use. This is especially important given the nature of our website. Our website is, in essence, “The Works of John Piper”—comprehensive and ever-growing. Therefore good categorization matters, as do consistent titling conventions, grammar, and so forth. Through good categorization, our site can be the complete Works of John Piper, easily navigable. Fourth, good categorization expands people’s horizons by exposing them to terms and groupings they would not have thought to search for—and probably couldn’t search for well, if they tried.

The Principles of Good Classification

Classification needs to follow solid principles if it is going to make sense and be useful. The characteristics of good classification, or grouping, are as follows:

1. Follow a classification scheme. Identify the common trait that you are using as the basis of your grouping. This is the classification scheme, or organizing principle—that which “defines the shared characteristics of content items and influences the logical grouping of those items.”[1] Classifications without a clear, definite, and consistent organizing scheme are confusing and reveal lack of clarity and understanding. See the document Desiring God Classification Schemes for a list of our major classification schemes.
2. Do not mix classification schemes. Multiple schemes can be applied, but they cannot be mixed. For example, you would not want to use this category structure: CDs, MP3’s, and Christian living. The reason is that the first two items are product categories, while “Christian living” is a topic. You could subdivide CDs, however, by topic, or provide “Browse by Topic” or “Browse by Product Category” as two alternate means of browsing.
3. Make the categories mutually exclusive. Categories should be mutually exclusive as much as possible. Otherwise, classification looses much of its value.
4. Make the categories unambiguous. It needs to be clear what the categories pertain to, especially since ambiguity in effect works against mutual exclusivity.
5. Eliminate redundancy. There should be no redundancy in labels, sections, and categories. For example, we should not have both “effectual calling” and “irresistible grace” as subject categories. If both terms are common, then by the least common one put a “see [name of the other term].”
6. Keep cross-listing to a minimum. This means that each item should be in only one category. This follows from the principle of eliminating redundancy.
7. Use “related items” sections to show people the full network of connections among resources. When an item seems to “fit” in more than one category, list it according to its primary category and designate it as a related item in other categories. This enables the item to be found, without making the user have to mentally sort each new category they go to in order to “screen out” the redundant elements.
8. Make the categories comprehensive. There should be no gaps. The categories should be exhaustive, without being redundant.
9. Seek to keep lists between 5 and 9 items. Groups of similar choices should generally be limited to 5-9 items; people can’t keep more in their mind for evaluation. If tons of links are needed, cluster them in groups of 5-9 links if you can. Of course, this is not always possible.
10. Make the groupings intuitive. The customer should not have to work hard to figure them out. One way to accomplish this is through user testing. In user testing, the key is to observe how something works with them, not necessarily to incorporate all of their suggestions.
11. Make the groupings logical. For the groupings to be logical means that they reflect the actual structure of the content. Since one of the purposes of categorization is to reveal the structure of the content, this principle is very important. At times, it may seem in conflict with making things intuitive. But in general, that which is logical is what is intuitive, or what will be found to be most intuitive upon use.
12. Create the categories to anticipate future content. It should be possible to add additional content without breaking the category structure.

When categorizing by topic, there are two specific principles that apply on top of the above principles:

1. Our topics should be universal to our organization. For example, we should not have one set of categories for products (online store), and a different set for resources (online library).
2. Our topics should be historical. We should seek for the categories to be informed by traditional categories of theology and the Christian retailing industry.

The Principles of Good Labeling

Categories that are designed well need to be labeled well. Many of the principles of classification imply as their corollary certain principles of labeling. Good labels are:

1. Short.
2. Clear.
3. Intuitive.
4. Jargon-free.
5. Not cute or clever.
6. Consistent in style, punctuation, presentation (fonts, sizes, colors, white space), syntax (they do not mix of verb-based and noun-based terms, they agree in parts of speech, verb tense, and they have roughly the same number of words), and granularity (they are all roughly equal in their specificity). 

Classification Methods

The classification type depends upon whether you “group” your categories or just list them all without groupings. To group your categories underneath larger categories is called the encyclopedic method. To simply list them all without major groupings is the A-Z method.

Both have benefits and drawbacks, and the choice of a method depends on the purpose. The best example of an A-Z method is the phone book. This method works best for known-item-searching. If you know you need a plumber, for example, you just want to be able to flip to a section called “Plumbers.” You don’t want to have to go to a major category like “Household Services” to find plumbers grouped with electricians and carpet layers.

But for non-known item searching, the encyclopedic method can be useful, because it groups like categories together. For example, if I am interested in the field of theology, I may want to see all theological topics grouped together—rather than having to sort through a lengthy list that includes many other types of topics, in the hopes of being able to identify and remember all the ones that pertain specifically to theology.

Classification Structures

When following an encyclopedic format, there are two main types of classification structures: the generic relationship and the whole-part relationship.

In the generic relationship structure, the relationship between the super and subclasses is always “IS-A.” An example of such a structure is:

• Automobile Companies
  • Ford
  • Toyota
  • General Motors

This is an “IS-A” relationship—Ford, Toyota, and General Motors are all types of automobile companies. According to “The Truth About Taxonomies,” an article in the Information Managmeent Journal, other characteristics of this type of structure are:

1. Inclusiveness. The top class includes the subclasses. Everything beneath it is a type of it.
2. Inheritance. Everything true of the given class is also true of all the items in its subclass.
3. Transivity. All subclasses are members of every class above them.
4. Systematic rules for association and distinction. All entities in a class are like each other in a predictable way.
5. Mutual exclusivity. Each item can belong to only one class.

In a whole-part relationship, each item of the subclass is a component of the super class. An example would be:

• Airplane
  • Fuselage
  • Engine
  • Wings

In this instance, the fuselage, engine, and wings are all parts of an airplane. You have a whole-part relationship.

If you mix classification structures, you often have confusion. For example, you would not want to create this structure:

• Airplane
  • Fuselage
  • Engine
  • Wings
  • Northwest Airlines
  • 747
  • DC-10

As can be seen, the problem with such a structure is that it does not adhere to a consistent classification. It mixes “Is-A” and “Whole-Part.” And among the “IS-A” relationships, you actually have two different kinds—Northwest Airlines is a type of airline, whereas the 747 and DC-10 are both types of airplanes.

Other Resources

This document provides the foundation for the two other documents in this series, Desiring God Topic Categories and Desiring God Classification Schemes. Some helpful external resources on classification are the following:

• “The Truth About Taxonomies,” The Information Management Journal (March/April 2003), 44-53).
• ECPA Christian Product Categories, 2003.
• Establishing Alphabetic, Numeric, and Subject Filing Systems, ARMA International, 2005.
• Information Architecture for the World Wide Web, Louis Rosenfeld & Peter Morville.

See also the other DG documents pertaining to classification:

• Desiring God Classification Schemes
• Desiring God Topic Listing
• The Nature of Our Topic Index

[1] Information Architecture for the World Wide Web, 55.