What function do these Java annotations serve?

Question

I\'m still not clear on the purpose of annotations in Java. Initially I thought they just served as documentation. But looking at this documentation from Google App Engine D

Answer 1

I think that these come from the Java Data Objects API. It's an API that overlaps to a degree with what EJB3 is supposed to accomplish. Same concepts, different syntax and tools.

If you are not familiar with annotations in general, check the Java tutorial.