An item in OAF is a java bean which allows a user to interact with the Oracle Apps Framework page e.g. a text box or a choice box etc.
Components or items are always placed inside some region so that they are always displayed as per the Oracle Application Framework standards. Every item or component has specific properties which can be given some values while creation of the OA Framework page e.g. rendered property which allows the bean to be displayed onto the screen it can be true(visible) or false(hidden). Items get rendered on the Oracle Apps Framework page in the fashion as described by the region in which that item has been placed either at declarative/design time or at run-time.
Even these properties can be changed at run-time, but that needs an understanding on how to import the beans and then how to create handle of the bean and then how to set properties. However this is not so much difficult to achieve but still some programming knowledge is needed to achieve this. This is called as run-time control of the bean and is explained in detail for every item in the corresponding item type.