  "Wiki rabbit holes" are informally defined as navigation paths followed by
Wikipedia readers that lead them to long explorations, sometimes involving
unexpected articles. Although wiki rabbit holes are a popular concept in
Internet culture, our current understanding of their dynamics is based on
anecdotal reports only. To bridge this gap, this paper provides a large-scale
quantitative characterization of the navigation traces of readers who fell into
a wiki rabbit hole. First, we represent user sessions as navigation trees and
operationalize the concept of wiki rabbit holes based on the depth of these
trees. Then, we characterize rabbit hole sessions in terms of structural
patterns, time properties, and topical exploration.
  We find that article layout influences the structure of rabbit hole sessions
and that the fraction of rabbit hole sessions is higher during the night.
Moreover, readers are more likely to fall into a rabbit hole starting from
articles about entertainment, sports, politics, and history. Finally, we
observe that, on average, readers tend to stay focused on one topic by
remaining in the semantic neighborhood of the first articles even during rabbit
hole sessions.
  These findings contribute to our understanding of Wikipedia readers'
information needs and user behavior on the Web.
