I hate posting the obvious, but it converts things. So, basically everything that is passed from the page back to the server is in
String format, so if there is a date or a boolean, that String has to be converted into the appropriate backing bean's type for those attributes.
Sometimes, you might not have a standard conversion between String and what type you have on the server, and you might have to create your own converter. So JSF has an interface and you write the code to convert the Form data into whatever object you need.
Mark
