Data Access Object (DAO) pattern is the most popular design patterns. It is used when you want to separate your presentation code from the code that accesses the back-end containing your data.

Data Transfer Object (DTO) is mere accessors ie, getters and setters used to fetch the data. It can be used independently of ActionForms to transfer data to the view.

when the huge data transfering from one layer to another layer which can be transfering whaen as individual value for multiple no. of times. it is recomended to combined all these values into a single value object and then transfer to another layer the special class of that single object which can store multiple values is calles values object