If you want to receive your Gmail emails, synchronize and backup your contacts, calendars, media or to simply download an app from the Play Store, you need to add your Gmail account on the LG G2.
This is how you add your favorite websites shortcut to your iPad or iPhone running iOS 7. It's a really useful feature if you are accessing some webpages frequently.
Windows Phone 8 enables you to choose the apps you want them to display its status on the lock screen of your phone. For instance a notification that you just got a new Gmail email.
With time it can happen you have a bunch of installed apps on your Windows Phone 8 powered phone you never use anymore, I suggest you to remove them to free some of the storage.
If you are on a certain data plan on your mobile provider, and don't want to exceed it, you can set data usage warning and a limit which can help you save some of your money.