what is the play store ?

Google Play (previously Android Market) is a digital distribution service operated and developed by google. It serves as the official app store for the Android operating system, allowing users to browse and download applications developed with the Android software development kit (SDK) and published through Google. Google Play also serves as a digital media store, offering music, magazines, books, movies, and television programs. It previously offered Google hardware devices for purchase until the introduction of a separate online hardware retailer, Google Store on March 11, 2015.
Applications are available through Google Play either free of charge or at a cost. They can be downloaded directly on an Android device through the Play Store mobile app or by deploying the application to a device from the Google Play website. Applications exploiting hardware capabilities of a device can be targeted to users of devices with specific hardware components, such as a motion sensor (for motion-dependent games) or a front-facing camera (for online video calling). The Google Play store had over 82 billion app downloads in 2016 and has reached over 3.5 million apps published in 2017. It has been the subject of multiple issues concerning security, in which malicious software has been approved and uploaded to the store and downloaded by users, with varying degrees of severity.
Google Play was launched on March 6, 2012, bringing together the Android Market, Google Music, and the Google eBookstore under one brand, marking a shift in Google's digital distribution strategy. The services operating under the Google Play banner are: Google Play Books, Google Play Games, Google Play Movies & TV, Google Play Music and Google News (formerly Google Play Newsstand). Following their re-branding, Google has gradually expanded the geographical support for each of the services.

Android applications

As of 2017^[update], Google Play features over 3.5 million Android applications.Users in over 145 countries can purchase apps, although Google notes on its support pages that "Paid content may not be available in some provinces or territories, even if the governing country is listed above." Developers in over 150 locations can distribute apps on Google Play, though not every location supports merchant registration. To distribute apps, developers have to pay a one-time $25 registration fee for a Google Play Developer Console account. App developers can control which countries an app is distributed to, as well as the pricing for the app and in-app purchases in each country. Developers receive 70% of the application price, while the remaining 30% goes to the distribution partner and operating fees. Developers can set up sales, with the original price struck out and a banner underneath informing users when the sale ends.Google Play allows developers to release early versions of apps to a select group of users, as alpha or beta tests. Developers can also release apps through staged rollouts, in which "your update reaches only a percentage of your users, which you can increase over time." Users can pre-order select apps (as well as movies, music, books, and games) to have the items delivered as soon as they are available. Some network carriers offer billing for Google Play purchases, allowing users to opt for charges in the monthly phone bill rather than on credit cards.Users can request refunds within 48 hours after a purchase if "something you bought isn't working, isn't what you expected, was bought by accident, or you changed your mind about the purchase".Apps meeting specific usability requirements can qualify as a Wear OS app.