Hi, Recently, I was faced with some questions which i fail to answer. can anybody tell me the right answer? 1) In EJB, we are using Custom Objects, which implements Serializable interface, for persisting the data. As it is marker interface, no method is defined in it. But still how the Custom object class uses readObject() & writeObject() method for saving state? & it is possible just by implementing marker interface only? What exactly it does internally? can any body tell me? Thanx in advance.