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Semantic-Based Navigation in Open Spaces 283
− Forward button, which works together with the back button but is used only marginally
in practice since users mostly return to previously visited pages.
− Home button, which is used only marginally in practice and enables users to return to
a known location in the information space (e.g., a search engine).
− History list, whose use is extremely limited as it only offers a simple list of recently
pages (e.g., today, last week or last month). Since it contains many pages, is not organized
in any sensible way and does not support searching, it cannot be effectively
used to revisit pages.
− Bookmarks, which allow users to mark a page for future reference and thus work as
a selective history list, which can be organized into folders and subfolders. While
some users use bookmarks to store already visited pages not suitable for further navigation,
bookmarks are good for future page revisits as they allow users to “search”
based on a hierarchical classification of folders. However, the number of bookmarks
greatly increases over time thus making effective bookmark management difficult,
and their overall usage and usefulness limited.
− History tree, which organizes recently visited pages in a tree instead of a list and provides
users with a good overview of their recent browsing history. Different approaches
exist, which may visualize the whole history for multiple sessions or only
the history of the current navigation session or domain. In (Nadeem & Killam, 2001)
the authors compare two tree based approaches (GlobalTree – shows the current session,
and DomainTree – shows individual domains) with the history list approach of
common web browsers and conclude that users prefer tree based history behavior instead
of history lists.
10.5.2 View-Based Navigation and Orientation Tools
Typically different navigation and orientation tools are employed in order to simplify user
access and improve user experience (Levene & Wheeldon, 2004):
− Link markers or embedded links are the basic means of navigation by means of inserting
and highlighting links directly into the presented information via text or images thus
corresponding to contextual navigation (Figure 10-9, D).
− Navigation bars contain a list of links and are often used for global navigation – site
menus on the left/top/right side of the page (Figure 10-9, A).
− Bread crumbs simplify the organization of information and display the user’s current
position in the information space together with the path that brought him/her there
(Figure 10-9, B). They improve user orientation and can be effectively used both for
global and local navigation.
− Tabs effectively subdivide the content into multiple parts and can be used for linear
local navigation (Figure 10-9, C).
− Site maps, as means for supplemental navigation, provide a global overview on the
main link and content structure of the information space (see Figure 10-10). A fisheye
view for sitemaps displays only the most relevant part of the map around the current
user position.