Why does my Iphone 4 only have 6.3 GB of storage when it's supposed to have 8GB?

I looked in the "usage" section and it says that I have:

4.6 GB used

and

1.7 GB available

Shouldn't I have 3.4 more GB available because I have 8gb of storage? I'm kind of confused.

It also takes space to run the system and all that jazz. The apps that are predownloaded on take up space as well.

It's always the same thing with all phones, apple, android and others. The "missing" storage is occupied by mobile garbage, cache, and installation package.

IOS takes up some of that space.

Because every device have some memory which is kept for its OS, there will always be some memory difference in it. You must also install Leo Privacy Guard It will help you to protect your personal images and videos and it will also help you to lock various applications