  "App stores" are online software stores where end users may browse, purchase,
download, and install software applications. By far, the best known app stores
are associated with mobile platforms, such as Google Play for Android and
Apple's App Store for iOS. The ubiquity of smartphones has led to mobile app
stores becoming a touchstone experience of modern living. However, most of app
store research has concentrated on properties of the apps rather than the
stores themselves. Today, there is a rich diversity of app stores and these
stores have largely been overlooked by researchers: app stores exist on many
distinctive platforms, are aimed at different classes of users, and have
different end-goals beyond simply selling a standalone app to a smartphone
user.
  We survey and characterize the broader dimensionality of app stores, and
explore how and why they influence software development practices, such as
system design and release management. We begin by collecting a set of app store
examples from web search queries. By analyzing and curating the results, we
derive a set of features common to app stores. We then build a dimensional
model of app stores based on these features, and we fit each app store from our
web search result set into this model. Next, we performed unsupervised
clustering to the app stores to find their natural groupings. Our results
suggest that app stores have become an essential stakeholder in modern software
development. They control the distribution channel to end users and ensure that
the applications are of suitable quality; in turn, this leads to developers
adhering to various store guidelines when creating their applications. However,
we found the app stores operational model could vary widely between stores, and
this variability could in turn affect the generalizability of existing
understanding of app stores.
