POJO - Plain Old Java Object
All JavaBeans are POJOs but not all POJOs are JavaBeans.
A JavaBean is a Java object that satisfies certain programming conventions.
*The JavaBean class must implement either Serializable or Externalizable.
*The JavaBean class must have a public no-arg constructor.
*All JavaBean properties must have public setter and getter methods (as appropriate).
*All JavaBean instance variables should be private.
