JSF: initial request and postback request?

Question

Please take a look at this below line of code in JSF

Quote from java.sun.com:

Answer 1

Initial request is the request that the browser does in order to display the page with the ${customer.name} tag. Postback happens when the browser posts some or all page values and then the same page that was posted in the first place is returned to the client. This might happen for example as a result of a validation error.

Knowing if the current view being rendered is a result of a postback is useful. For example you might want to display a message as a result of a postback, but not every time the page is refreshed.