If you frequently purchase apps and games on your iPhone or iPad, you may find yourself running out of space or cluttering up your Home screen with icons you barely launch anymore. Most people say they don't delete apps and games in fear of not being able to get them back. Luckily, thanks to iTunes in the Cloud, part of iCloud, you can easily re-download any apps or games you previously purchased whenever you'd like, at no additional cost to you.
How to download a previously purchased app you deleted on your iPhone or iPad
Source: iMore
