Papers in PDF format

the navigation tools from every document in your web site.
The links to the navigation tools should be clearly labeled and consistently located. While some icons are likely to be
recognized by most people, most graphical symbols that stand for abstract concepts are ambiguous, unclear, and even
misleading. You may think that users can learn what your icons represent, but you shouldn't depend on it: always label
your icons with helpful text.
If all of your documents are very brief (about one screenful), then you can place the links to your navigation tools at the
beginning or end (consistently one place or the other!) of each document. If many of your documents are two or more
screenfuls in length, then I recommend that you place links to your navigation tools at both the beginning and end of
each document.
Link to the Home Page and Reference Pages of Your Web Site
It is customary to offer a link to the first document (home page) of your web site as a navigation aid. Users expect to be
able to orient themselves by returning to this top-level document because good home pages typically provide useful
information about and links into the web site.
If your web site provides other documents dominated by useful links--reference tables for example--you can help users
by offering standard links to those documents along with your other navigation tools.
When To Use "Previous" and "Next" Links
Many web sites are easy to organize into a linear sequence because that is how they were conceived and implemented. If
your site provides information in a well-defined order, and if this order is necessary for users to obtain full benefit from
your site, then a "previous" link at the beginning of the document and a "next" link at the end of the document is
appropriate.
However, just because you can define a sequence for all the documents in your site does not mean that you should
include previous and next links. These links imply to users that the linear sequence is important for understanding the
material. You should include them only if this is true.
A Table of Contents is Highly Recommended
A table of contents is an almost universally understood navigation tool. It outlines any body of work by listing
document titles, headings, and sometimes subheadings. Low-level subheadings are normally not included in the table of
contents because they can expand the table of contents to an unwieldy length.
Many users who are new to hypertext documentation feel welcome when they find a web site's table of contents because
it is comfortable and familiar to them. It also helps introduce them to the benefits of hypertext links because they no
longer have to look for page numbers to find the information they need.
The linear-sequence model of your web site provides your table of contents.
You can add levels of meaning to your table of contents by indenting subordinate or supporting titles and headings
under the more general titles and headings. An indented table of contents maps perfectly to a hierarchy chart, and vice
versa. That is, if you can organize your documents into an indented table of contents or a hierarchy chart, then you can
and should! provide both for your users.
Hierarchy Charts Offer Numerous Benefits
Hierarchy charts may differ from tables of contents in the amount of links they provide. Hierarchy charts can provide a
spatially organized overview of an entire web site: users can see the structure of the site in a single overview. And
through image mapping, you can let users move directly to any document in the web site by pointing and clicking on
the titles in the chart. But for larger web sites, there is no room for long titles or too many entries on the chart.
So titles will need to be shortened for use on the chart. And more headings will probably need to be omitted. But even if