Help me to understand annotations

[Hussein Baghdadi]

Hi all.
I have been reading the annotation page at java.sun.com , but I understand nothing...
look at the following example please :

public @interface Copyright {
    String value ();
}

the page says :
In annotations with a single element, the element should be named value to avoid having to specify the name when the annotation is used.
would you explain please ???
the page continuing :
After an annotation type is defined, a developer can use it to annotate declarations in code:

@Copyright("2004 My Corporation")
public class Converter {

I didn't understand the effect of the previous lines, would you explain please ??
does it mean that Converter class is implementing Copyright interface ?
understadning annotation is a vital subject to me as EJB 3.0 will be built using this approach, so would mind helping me to understand this technology ?
thanks.