  Hundreds of millions of people learn something new online every day.
Simultaneously, the study of online education has blossomed within the human
computer interaction community, with new systems, experiments, and observations
creating and exploring previously undiscovered online learning environments. In
this study we endeavor to characterize this entire landscape of online learning
experiences using a national survey of 2260 US adults who are balanced to match
the demographics of the U.S. We examine the online learning resources that they
consult, and we analyze the subjects that they pursue using those resources.
Furthermore, we compare both formal and informal online learning experiences on
a larger scale than has ever been done before, to our knowledge, to better
understand which subjects people are seeking for intensive study. We find that
there is a core set of online learning experiences that are central to other
experiences and these are shared among the majority of people who learn online.
We conclude by showing how looking outside of these core online learning
experiences can reveal opportunities for innovation in online education.
