Newer models of iPhone and iPad have preinstalled default applications package iWork / iLife, including iMovie, Garageband, among other utilities. While this is a large collection of applications, many users who do not normally use (or at least the vast majority of applications) and can choose to delete these apps to get enough additional storage space available, which is almost 3GB of storage in this case.
If you do not normally use this application suite, you can get rid of them to free up space on your device. You can easily see if iWork suite occupies a considerable amount of storage or not, entering Settings -> About -> Application -> manage storage.
If you decide that the suite of applications are not useful to you, you can choose to delete the apps in the same way as other iOS applications are uninstalled. While this removes the apps on your iPhone or iPad, they will remain linked to your Apple ID, which means you can download them at any time without paying.
At least, knowing that you can recover quickly about 2.7 GB of storage by removing these applications from your iPhone, the future will know what to do if you get the warning message "storage" when trying to take a photo or download a new application.
If you like to have in your device this series of applications and you have no storage space problems will not have to do anything in particular, just leave everything as it is.
Note that iWork applications are not preinstalled default iPhone models 16GB and 8GB, because they can not really afford space consumption. This means that only find these applications preinstalled on devices 32GB, 64GB, 128GB and 256GB.