The EL expression
"zar.boo.baz" points directly to the
baz property (Hello!) within the first tree. The EL expression
"tar.too.0.taz" points directly to the
taz property (Hello again!) within the second tree.
At heart EL expressions provide a very loosely-coupled way of accessing properties and functions within an object tree. EL expressions are typically evaluated at run time, allowing for very late binding. EL expressions are accepted and processed by certain core Framework Functions.
For more information, see Framework Concepts#EL.