Dependency Injection ,Repository Pattern

Question

Hi,

 

I am learning asp.net MVC from tutorials.

I made data models using code first approach then use scaffolding for CRUD operations and it will automatically generate all the codes.

It is good to use scaffolding or write your own codes.

I also heard about Dependency injection, Repository pattern but don't know about this why it is used and how to use.

What is the use of ViewModels?

 

To develop an application, which is good approach use dependency and repository or just develop the application without using it and use scaffolding technique.

 

Thanks ..