You are trying to install or open an app that didn't come from the Mac App Store but you got a message saying App can't be opened because it is from an unidentified developer. This is how you bypass it.
A really useful feature in case you want to receive a warning notification before you use all of the mobile data available according to your mobile provider contract. It's a great way to avoid additional charges.
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.
Google spreadsheets lets you create charts and graphs to visualize a data set. Let's take a look how to create a nice and simple chart in a matter of few clicks.
