Wikipedia
SWFAddress is an open-source JavaScript library that enables Adobe Flash/ Flex and JavaScript/ AJAX websites and web applications to support deep linking, a practice that enables users to link to a specific section or page of the content.
Its importance is because such Rich Internet Application platforms provide only a single URL to access the specific content, and any user navigation within the content cannot be uniquely identified, or shared by means of the URL.
When the developer of the content integrates with SWFAddress, users are able to use standard browser navigation functionality, share and bookmark unique URLs that represent the currently displayed section or state of the content.
The library is commonly used on Flash websites and web applications being the only available deep linking JavaScript library for Flash on the web. SWFAddress has been found to be used by over 100,000 websites as of 2011.