Is core data is a kind of Graph Database?

I am required to develop a big application,required to know graph database concepts the link http://ift.tt/1E8O3yh am planning to use core data instead of above link frame work. I want answerers for the following questions.

1)What is Graph Database exactly?.Explain with simple general example.which we can not perform with sqlite.

2)Does core data come under relational data base or not ? Explain.

3)Does core data come under Graph Database? But in apple documentation they mentioned that core data is for object graph management.object graph management means Graph Database .If i want to make relation ships ,weighted edge between objects core data is suitable?.