The term mobile app store defines a web-based sales platform for applications. Within app stores users have the opportunity to search for, download, purchase and update mobile apps for smartphones or tablets.
Leading Mobile App Stores
The most known mobile app stores are Google Play Store (former Android Market) and iOS App Store (Apple App Store).
Launched in 2008, Apple App Store is not only one of the leading mobile app stores, but the oldest one. It is run by Apple and is the only opportunity to download iOS Apps for iPad, iPhone or iPod from third-party providers.
Google Play Store so far is the leading mobile app store for Android apps. It was launched in 2008 with the name Android Market shortly after Apple’s app store. In the year 2012, they changed their name from Android Market into Google Play Store.
Windows Phone Store, former Windows Phone Marketplace is the only mobile app store available for app running on smartphone OS Windows phone by Microsoft.
The newest among leading mobile app stores is Amazon App Store offering Android apps since 2011 on Amazon platform. Although it shares the android market with Google Play Store, Amazon so far could not overtake the android market established by Google.
ASO Differences in Mobile App Stores
With 1.5 million available apps as of 2015,  Google Play Store is the leading store for Android apps. In second place comes Apple’s App Store which offers 1.5 million iOS apps.Both leading stores have complex searching and sorting algorithms implemented. However, there are minor differences in some ASO factors. Apple App Store, for example, provides you with an explicit keyword field. Keywords within this field show the algorithm, which words a user might use if searching for your app. Google Play Store’s searching algorithm, in turn, parses your app description and title to find relevant keywords.