versionCode — A positive integer used as an internal version number. This number is used only to determine whether one version is more recent than another, with higher numbers indicating more recent versions. This is not the version number shown to users; that number is set by the versionName setting, below. The Android system uses the versionCode value to protect against downgrades by preventing users from installing an APK with a lower versionCode than the version currently installed on their device.