What is an APK File? Just like Windows PC systems use a .exe file for installing software, Android does the same. An APK file is the file format used for installing software (usually games or apps) on the Android operating system.
When you install applications from Google Play (formerly known as Android Market) everything is automated and you don’t get to know where the files are being downloaded, what is the extension of the file and how the installation is being performed. So as long as you are using Google Play alone to install apps on your Android, you don’t have to worry about a thing. But there may be instances when you want to install an application manually, could be a beta application from developer’s website or maybe your friend transferred it to you over Bluetooth.
There are many sources of APK files across the web, but be sure to choose a site which you trust. Some APK files may contain malicious software (malware) which could compromise your phones security, so it is best to be cautious before downloading or installing any app from outside of the Play Store (and even in the Play Store you’re not completely safe!). Generally speaking, APK files found on sites like XDA should be safer to download than from elsewhere, but read some reviews and user comments before downloading or installing an APK.
You must find an APK file that you want. Search online for an APK file and download it to an easy-to-find location on your computer (like your desktop). Before you can install it on your phone you will need to make sure that third-party apps are allowed on your device. Go to Menu > Settings > Security > and check “Unknown Sources” to allow your phone to install apps from sources other than the Google Play Store. If you like, you can also download an app like ES File Explorer so you can easily find files on your Android device.
Once you have downloaded the file on your computer, connect your device to it. At this point, you may be asked if you simply want to charge your phone or connect it as a “media device.” Choose “media device”. Then, simply find your phone’s folder on your computer (it will be in “My Computer” or “Computer” on Windows machines) and copy the APK file into a folder of your choice in your Android smartphone.