Improved DAO Javadoc

dao/src/main/java/com/iluwatar/dao/App.java

@@ -5,8 +5,14 @@ import java.util.List;
 
 /**
  * 
+ * Data Access Object (DAO) is an object that provides an abstract interface to some type of database or other 
+ * persistence mechanism. By mapping application calls to the persistence layer, DAO provide some specific data 
+ * operations without exposing details of the database. This isolation supports the Single responsibility principle. 
+ * It separates what data accesses the application needs, in terms of domain-specific objects and data types 
+ * (the public interface of the DAO), from how these needs can be satisfied with a specific DBMS.
+ * <p>
  * With the DAO pattern, we can use various method calls to retrieve/add/delete/update data without directly
- * interacting with the data. The below example demonstrates basic operations(CRUD): select, add, update, and delete.
+ * interacting with the data. The below example demonstrates basic CRUD operations: select, add, update, and delete.
  * 
  */
 public class App {