title: What is the difference between variable, parameter and field in JasperReports?
body: <p>I am a newbie to <em>JasperReports</em>, have been working on some small samples. It seems "Fields", "Parameters" and "Variables" are very commonly used to demonstrate dynamic data and looks much alike. So can I ask what's their difference specifically in <em>JasperReports</em>?</p>
  
  <p>I guess variable is something defined within a Jasper report and can dynamically change. Parameter is something taking from external source (Java..etc), field is for entities (database schema, class entity), but I don't think my understand is all right.</p>