How to increase the storage from 6.35g in my Iphone 4?

I'd like to be able use the full storage, minus the ios, in my Iphone 4. Now I have 6.35 available and have 5.95 "free". What is using.4g? I haven't "jailbroken" yet. Will doing so increase the storage?

Well most of that memory is being used by text messages call logs and contacts and varios thing from.go clear recents in your phone app and delete old text maessages then go to settings safari and delete history and cookies i hope i helped