APK stands for Android Package (sometimes Android Package Kit or Android Application Package). This is the file format that Android uses to distribute and install applications. It contains all the elements that an application needs to be properly installed on your device. APK files are applications for Android devices, and cannot be installed on an iPhone.
Downloading APKs from sources other than the Play Store is useful, but you can't do much with APKs on platforms other than Android unless you install an Android emulator like Bluestacks. When the application is ready for shipping, Android Studio compiles it and then places it all in one container: an APK. The only way to make an Android application run on an iPhone would be to make the iPhone run Android first, which is not currently possible and would never be sanctioned by Apple. Normally, when you visit Google Play and download or update an application, the store automatically installs the APK for you. Now, iPhone users are slowly discovering this platform where they will find and share applications in the IPA format, the native iOS file extension for iPhone and iPad. To open the apk file and consider the individual files in it, you will use an application that corresponds to the format of the extracted file. While Google Play has filters to detect dangerous applications, there isn't as much protection when you install APKs on your own.
TutuApp is the main unofficial app store that offers third-party apps and games on iPhone and Android devices. All APKs are essentially ZIP files, but they must contain additional information to function properly as an APK. When you open an APK on your device, it contains instructions for installing it on your phone and provides information about the package itself to your device. But APKs power every download on your phone, so you take care of them all the time, even if you don't realize it. Take the APK you want to install (whether it's the Google application package or something else) and place the file in the tools folder of the SDK directory. In conclusion, APKs are a great way to get access to a wide range of apps and games for Android devices.
However, they cannot be used on iOS devices such as iPhones or iPads. If you want to use apps from outside of Apple's App Store, then you will need to use an Android emulator like Bluestacks.
