Difference between Bean, Enterprise Java Bean and Managed Bean

Java Beans:
JavaBeans components (beans) are reusable software programs that you can develop and assemble easily to create sophisticated applications.
Practically, they are classes written in the Java programming language conforming to a particular convention. They are used to encapsulate many objects into a single object (the bean), so that they can be passed around as a single bean object instead of as multiple individual objects. A JavaBean is a Java Object that is serializable and allows access to properties using getter and setter methods.

EJB
Enterprise JavaBeans (EJB) technology is the server-side component architecture for Java Platform, Enterprise Edition (Java EE). EJB technology enables rapid and simplified development of distributed, transactional, secure and portable applications based on Java technology.


MJB
The Managed Java Bean represents a resource running in the Java virtual machine, such as an application or a Java EE technical service (transactional monitor, JDBC driver, etc.). They can be used for getting and setting applications configuration (pull), for collecting statistics (pull) (e.g. performance, resources usage, problems) and notifying events (push) (e.g. faults, state changes).