In Java EE 6, Expression Language supports both immediate and deferred evaluation of expressions. Immediate evaluation means that the expression is evaluated and the result returned as soon as the page is first rendered. Deferred evaluation means that the technology using the expression language can use its own machinery to evaluate the expression sometime later during the page’s lifecycle, whenever it is appropriate to do so.

Expressions that are evaluated immediately and the expressions whose evaluation is deferred use, respectively, the syntaxes