What is the Hierarchical database model. How does it work? Why we need the Hierarchical database model? When we can use it? Where we can use it? What does Hierarchical database model. Based on?...

What is the Hierarchical database model.
How does it work?
Why we need the Hierarchical database model?
When we can use it?

Where we can use it?
What does Hierarchical database model. Based on?
Examples: tables, schema, and how does it create?
Advantages and disadvantages?
References