When to use Factory method pattern?

Question

When to use Factory method pattern?

Please provide me some specific idea when to use it in project? and how it is a better way over new keyword?

Answer 1

Although this isn't necessarily it's primary use, it's good for something where you have specialized instances of a class:

public ITax BuildNewSalesTax()
public ITax BuildNewValueAddedTax()

You need both methods to build a tax object, but you don't want to have to depend on using "new" everytime because the constructors may be complex. This way I encapsulate all of the changes into a single method that is clear to others for future maintenance.