Why download GApps? You need to download Gapps when you install a custom ROM on your Android phone, tablet, TV or watch. Most custom ROMs are built using the AOSP (Android Open Source Project) code. And since AOSP is completely independant of Google services, you need to install Google services and apps (GApps package) separately. Some of the popular ROMs that require GApps are: CyanogenMod / Line