Class, Methods Attributes

[sumit84.mca]

Hi all,

Take this example :

[WebMethod]
public DataSet getData()
{
return dataset;
}

I want to know, in the above example, how does the Attribute [WebMethod] work. What is the role of this(any attribute written in this pattern above function/class) attribute?

More abstractly I want to know the how does the Attributes work?