Android applications are stored in a format that uses the APK file extension. Although you usually need a file conversion program or service to convert one type of file to another, they are not very useful when it comes to APK files. However, be careful when downloading APK files from other sites, as some may be trying to install a backdoor on your phone. If you have problems, you can always try to download the APK file directly from the Google Play Store. I encountered a problem when I was searching for an application, but it was in My Apps so I could reinstall it on my new mobile phone;).
Fortunately, it is possible to open APK files on a PC using cross-platform programs or Chrome extensions. Knowing this is essential if you want to start downloading filtered apps or customizing your Android experience more than what is possible with the Play Store alone. I suggest that you save the ones you like because older apps tend to disappear from the Play Store, but they will continue to work on most newer distributions. Worse, incomplete APK files can contain malware, as many who thought they were getting the first versions of Fortnite for Android found out with dismay. You can also search for specific APK files with ES File Explorer, but keep in mind that the naming convention may change in future versions.
APK is also an abbreviation for some terms that are not related to Android applications, such as the administrator's private key and the amplitude phase key. If you have an Android device, chances are you've heard of an APK file at some point and wondered what it is. It's perfectly legal to download APK files and use them to install applications from outside the Google Play Store. Or you might even dislike a particular application after an update and want to install an older version instead. This is because an APK file is an application created to run only on specific devices, unlike other file types, such as MP4 or PDF, that work on a variety of platforms.
Opening an Android app on your Android device only requires that you download it as you would any file and then open it when prompted.