Persistence allows Microsoft Internet Explorer 5 and later to retain Web page information, styles, variables, and state. For example, a collapsible list of links within a table of contents can remain expanded to the user's choice upon leaving and later returning to the page. Or, a search engine query form can retain the last-used search string.
Persistence is implemented as a behavior .
Persistence creates new opportunities for the author. Information that persists beyond a single page without support from the server, or within the finite scope of cookies , can increase the speed of navigation and content authoring. These behaviors can be used to preserve information in the browser's history, in favorites, in an XML store, or directly within a Web page saved to disk. When a user returns to a persisted page, the state of the page can be restored. By allowing information to safely reside on the client, fewer server transactions are required.