Specialties: Web Sites
A-Z Web Site Indexes Explained
(Originally published December 6, 2004 on Sitepoint.com)
By Heather Hedden
A-Z Indexes are far more accurate than search engines for searching the
content of a web site or intranet. For the value they can bring to a site,
A-Z indexes are worth the additional cost, but, if you decide to add an
index to your site, i’s important to find the right person to do
How alphabetical indexes work
An A-Z Index offers an alphabetical list of “entry point”
topics through which the user may browse and select. In an index at the
back of a book or manual, the entries are followed by page numbers. On
a web site, the entry points are hyperlinked to the appropriate pages,
and often to named anchors within Web pages for an even greater level
of detail in indexing.
As with book indexes, a site index may contain multiple entries, each
worded differently, that point to the same page, or page and anchor. This
approach is used to cover all the different ways a user may think a topic
is named, and is referred to as “double posting.” It covers
synonyms, such as “cars” and “automobiles,” and
the different word order of a phrase, such as “automobile engines”
and “engines, automobile.” The browsable nature of the index
solves the problems that might arise from incorrect or variant spellings,
and singular vs. plural usages that the site user might choose.
In addition, there is often a second level of terms, called “sub-entries,”
that are listed and indented under some of the main entries.
A Web A-Z index is typically a single, long HTML page, although it could
be broken into separate pages for each letter of the alphabet if it were
extremely long. At the top of the page, a horizontal list of the letters
of the alphabet usually appears. The user makes a selection from this
list, and jumps to the appropriate section of the alphabetical index.
A-Z indexes are created not by machines, but by humans who take care
to add index entries only to pages on which good information about the
topic appears. In this way, the indexing of topic words mentioned in passing
or out of context is avoided, boosting the overall relevance and quality
of the index itself.
A list of some examples of A-Z indexes can be found at A-Z
Indexes on the Web: An Annotated Sampler from the Montague Institute
Better than Search Engines
Every now and then, we find an article or other document that says site
indexes are a good thing. And every now and then we may come across an
A-Z index on a web site, and think, “Hey, that’s cool.”
So, why don’t we see more of them? The simplest answer is that the
big competitor to A-Z indexes -- site search engines -- are usually cheaper
(or may even be free) to implement. But, in the end, you get what you
Site search engines may not retrieve enough or any pages.
Whole-Web search engines usually produce “satisfactory” results
in the quantity of pages, as users generally want “some information
about” a subject, and this can typically be found on some of the
numerous pages retrieved. If many good pages are missed by the search
engine, the user usually does not notice or care, since enough other good
pages are found.
Within a web site, however, the number of pages is relatively small, so
a simple search engine search might not yield enough or any results, even
if there are good pages on the subject. This is most likely to occur because
the search subject the user enters is worded differently than references
to that topic within page text.
Site search engines may retrieve too many irrelevant pages.
Whole-Web search engines usually produce “satisfactory” results
in the quality of articles, since the major search engine companies have
developed complicated criteria and algorithms for the retrieval and ranking
of pages. Off-the-shelf search engines to be used within a site are not
so sophisticated. They often retrieve pages that include a mere passing
mention of the search term, but do not really focus on the subject at
Search engines often cannot meet the higher demands that
searchers have for searches within a site.
Searchers of a site may want all the information a site has on a given
topic, whereas searches of the entire Web only want -- and expect -- some
information on a topic. Searches of a site may also want to find the information
more quickly, since they might be looking at a number of sites simultaneously.
In the end, the quality of the search engine results reflects the sophistication
of the search string entered by the user, which cannot be controlled.
In the A-Z index, on the other hand, the quality of the results reflects
the sophistication of the indexer, which can be controlled.
Additional advantages to A-Z indexes
In addition to the superior search accuracy, A-Z indexes offer other
- The large number of well-labeled internal links that make up an A-Z
index increases the search engine optimization rating of the linked
pages and, consequently, that of the entire site.
- The absence of irrelevant pages retrieved make the index searching
more efficient, enhancing the usability of the web site
- The ability to browse the index enables users to digress and explore
other topics that catch their attention, keeping them on the site longer.
In other words, indexes can enhance the “stickiness” of the
site. Finally, A-Z indexes can be effectively implemented on web sites
that are too small to work with site search engines, such as sites in
the range of 20-50 pages.
No more costly than customized search engines
Of course, basic site search engines can be made more effective with
tinkering. They can be customized to search only meta tags, and meta tags
can then be carefully written for each page. Searches can be restricted
to certain pages and/or zones within pages. Results can be tailored to
display “key-words-in-context.” All this customization requires
the expertise of Web developers, whose time is not cheap. And the improvement
in the search engine’s capabilities can still never match those
of a carefully crafted A-Z index.
Creating an A-Z index, on the other hand, is a straightforward editorial
task that can be completed by a freelance indexer. Indexers can provide
an accurate quote of the job before it begins, based on the average number
of words per indexable page or the number of entries in the index. Depending
on the size of the web site or intranet, you can expect an A-Z index to
cost between $200 and a $1000.
Getting the right person for the job
It’s very important that an A-Z index be done well. Although any
alphabetical list might look good at first, if users cannot quickly find
what they’re looking for, they will become frustrated with the index
and the site itself. It would probably be better to have no index at all
than a poorly created one.
Should you create the index yourself? Creating an index is more complicated
than creating a hierarchy of categories or a taxonomy. To become competent
at indexing really requires appropriate education. Information architects
with backgrounds in library science and a good sense of labeling, however,
could probably pick up indexing from reading a good book on the subject.
In addition, a tool for automatically embedding the index URLs, such as
HTML Indexer, which is my preference, is recommended.
So, where do you find a web site indexer? If you don’t want to invest
the time and energy in learning indexing yourself, it’s probably
best to contract a freelance indexer. Most of the professional associations
of indexers listed below maintain searchable databases of freelance indexers.
Limit your search to HTML or Web indexers. The nice thing about web site
indexes is that samples of an indexer’s work are usually accessible
online, so you can easily evaluate a potential indexer’s work.
It’s true that manually created A-Z indexes need to be updated
when pages are added to or removed from the site, but so do site maps.
If a web site is so large and dynamic that it is impractical to maintain
a site map, then it would also be impractical to create and maintain an
index. For pages that have frequently changing content, such as an announcements
page, an index should be written not to the specifics of the content,
but merely to the general concept of announcements, so that frequent updates
in the index are not needed.
If the index is created by a contracted indexer, an agreement needs to
be reached about how the index will be maintained. Either the indexer
can be retained for future updates, or the indexer can provide written
guidelines to the webmaster on how to maintain the index. For example,
after writing an index to a school’s web site, I identified the likely
additional future pages and wrote up guidelines for the webmaster to indicate
the entries/subentries under which the new pages should likely be indexed.
In this case, the new pages tended to be individual class pages, each
of which would have been best indexed in three places: under the teacher’s
last name, by grade level, and under the topic “classroom pages.”
A-Z indexes will enhance the searchability, usability, and overall quality
of a web site with results that are superior to most site search engines.
Just because a search engine is free, don’t be tempted to keep it
on the site once you've added an index. Since they serve the same purpose,
the presence of both a search engine and an A-Z index, yielding differing
results, would only confuse users and waste their time.
Resources on indexing
Resources on indexing, including lists of courses and books on the basic
indexing skills, are available through the professional indexing associations:
© 2005 Heather Hedden