How does the google playstore and Aptoide App store directly install apps on the phone rather than d-CodePudding

I am curious to know the technology behind automatic installation. Apps from google playstore get installed automatically. Moreover, 3rd party app store Aptoide also has this feature of automatic installation where the apk file needs not to be manually installed. How does this happen? Is there any certain API function or back end code for this?

Thanks

CodePudding user response：

The play store does download the APK file. It just has a permission that allows it to install apps without asking permission. Any system app can get that permission- INSTALL_PACKAGES.