referenced project, j2ee dependency module, java build path

[ben oliver]

I think I need some help in understanding the difference among the following three things of an EAR project in eclipse or any other similar IDE --

1. Java Build--> Project: In Java Build property, you can add another IDE project here. Under what condition do you need to add a IDE project here ?

2. J2EE dependency module --- You can also add a standalone java Project here. For what purpose do you need to add it ? I found that, if my j2ee project uses a stand alone project, I have to add that stand alone project here, otherwise the whole project can build well but at run time, it gives NoClassFOund error, can you tell me why ?

3. Project References --- If you add a project here, what does it exactly mean to you ?

Thanks !