Deep Linking is a term that describes the support for URL based navigation in applications that are not a collection of HTML pages.In Flex 3, Deep Linking is implemented using fragments, the portions of URLs after the “#”. For example, in this link http://mysite/page.html#view=1 the fragment is view=1.

Adding support for Deep Linking to your Flex 3.0 Application is relatively simple. The basic steps are:

1. turn off the HistoryManager (the HistoryManager also uses the BrowserManager and will interfere with your fragment processing).
2. initialize the BrowserManager with a default fragment and title
3. determine when you want to update the fragment and call BrowserManager.setFragment.
4. listen for events from the BrowserManager
5. when you receive an event, interpret the fragment and change your application accordingly

Deep linking only works with certain browsers. The following browsers support deep linking:

* Microsoft Internet Explorer version 6 or later
* FireFox for Windows and Macintosh
* Safari for Macintosh

Some great links for deep linking with examples:
Handling Flex 3’s deep linking in a Cairngorm architecture
Deep Linking with TabNavigator
Deep Linking with ToggleButtonBar