What I've called "structure" comes under many names, the most familiar
of which are probably "hierarchy" or "information architecture".
Whichever word you use, structure encapsulates the relationships
between the components of a site that people use to find their way to
the information they seek.
Structure is simple to define but devilishly tricky to create at times.
A successful site structure must create what psychologists refer to as
a "schema": a mental model that visitors can use to understand where
you've hidden the content I discussed in previous columns.
To create a successful structure, you must understand your audience
well enough to know what kinds of schemata they can benefit from.
Structures fall into four broadly familiar categories, each of which is
based on a schema so familiar that readers can use it without much
thought to find what they're looking for: ordered (alphabetical or
numerical), functional, hierarchical and Web.
Ordered structures use our knowledge of some inherent order to help us
know where to look. Alphabetical structures are the most familiar, and
use the well-known order of the English alphabet to find information
that can be defined by its position in the alphabet; dictionaries and
encyclopaedias are the obvious examples of such structures. Numerical
structures rely on the familiar sequence of numbers; products grouped
by price and historical data arranged in timelines are obvious
examples. Many other "orders" exist, including physical (e.g. a
geographical map, a blueprint of a house), logical (e.g. you can't
print your document until you've turned on the printer), and
organizational (e.g. the well-defined ranks in a military organization).
Functional structures rely on the human ability to group things based
on similarities in their function or purpose. One familiar example
might be the Web site of a company that sells several products, and
devotes a separate part of the site to each product. Companies that
sell computer-related materials on the Web, for example, typically
divide their site into at least three different functional groupings:
hardware, software, and consumables.
An equally logical functional structure might be to gather all the
products for printers (the printers, paper and ribbons, and printing
software) in one area and gather storage products (disk drives,
diskettes, and disk utility software) in another. Which approach makes
the most sense depends on how your audience will approach the site.
Hierarchical structures depend on our ability to recognize how broad
groups can be subdivided into narrower categories, each of which can in
turn be subdivided into other categories, with the items grouped under
these categories becoming more similar the further down the hierarchy
you go. Organization charts represent a good example of a hierarchical
structure, though as I noted above, they can also be ordered if the
hierarchy is clearly defined. Hierarchies differ from ordered
structures in that their order is arbitrary, based on degrees of
similarity rather than a universally acknowledged sequence; for
example, technical communicators fall under product development in some
companies, under sales and marketing in others, and stand as their own
department in others.
Web structures are the source of the name for the World Wide Web
itself: highly interconnected, with a bewildering variety of links
between related topics. In Web structures, as in the Web itself, paths
potentially exist between any two related topics. The problem with such
structures is that their unparalleled flexibility comes at the cost of
unpredictability: nobody knows all possible paths, nor even the best
path to a specific piece of information.
In practice, most sites combine all four structures, with the most
appropriate structure chosen for each component of the site. To link
these structures, you can rely on familiar, time-tested schemata: a
table of contents (such as a site map) to provide a high-level view of
what structures exist on your site, and an index that provides a low-
level view of individual topics for those who aren't interested in the