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276 Selected Studies on Software and Information Systems
− Faceted navigation – the browsing via a view-based interface employing a faceted classification
of the information space (effectively a forest), such as searching for job offers
or products in an online shop.
In practice, individual navigation models correspond to different navigation types and are
realized using different navigation and orientation tools (see Section 10.5), which when
placed on a web page allow users to choose from a variety of navigation options.
10.3.1 Navigation Types
We distinguish different navigation types within an information space:
− Local navigation, which links nodes in the current information subspace (e.g., a cluster
of similar nodes) and allows users to navigate in the nearby vicinity of their current
position.
− Global navigation, which is persistent throughout all views (e.g., web pages) and links
the current view with landmark nodes in the web graph thus providing quick access
to all major hubs in the information space.
− Contextual navigation, which links related nodes throughout the information space
and is often realized as contextual links within the text or as lists of “see also” links.
− Supplemental navigation, which includes other navigation tools such as site maps, indexes
and guides. These include special nodes with high out degrees as well as specially
created sequences of nodes (trails).
10.3.2 Linear Navigation
Linear navigation is a straightforward navigation approach used mainly for local navigation
in unstructured information spaces, when browsing lists of data (e.g., search results)
or when following (pre)defined navigation trails (e.g., guides). This translates to local navigation
along a path in the web graph, which has few outgoing edges, “ideally” only one
per node (or two for reciprocal navigation).
During linear navigation, users successively browse one page after another. “Straight
line” linear navigation allows users to proceed to the next page in the sequence (see Figure
10-3), whereas reciprocal linear navigation also supports backward links to previously visited
pages (see Figure 10-4).
Figure 10-3. The linear “straight line” navigation model supports one-way linear movement
in an information space.
The disadvantage of linear navigation is that it takes too long to examine all available data
and the user usually has little information about the content of the following pages. For
example, during search results browsing most users view only the first page, while only
few go beyond the second or third page. One possible advantage of linear navigation is its