2. Online data storage system
The most instant method for keeping your data intact with yet a significant amount of available storage on your iPhone is the iCloud. This online service connects you and your iPhone in amazing ways. iCloud drive stores all the photos, videos, music and other documents securely and you can access them from your iPhone, iPod, iPad, Mac and even from your PC. Thus, you can store your desired files on this drive and remove them from your phone to make extra room. iCloud drive app is built in iOS 9 which gives you 5 GB of free storage, 50GB for $0.99 a month, 200 GB for $2.99 and 1TB for $9.99 per month.
Some more such drives are Google drive and Dropbox which might come handy in situations when you have no other option than to erase your important files. So instead of completely losing access from them you can rather keep a backup using these online services. Google drive allows the user to store up to 15GB for free and you can extend further with their monthly plans at $1.99 per month for 200GB that stretches to $299.99 per month for 30TB of storage. Dropbox, on the other hand, is integrated with iPhone, iPod, iPad providing free storage space of 2GB with an extension of 1TB at $9.99 per month.