Tunetext Builder breaks your HTML page up into a set of separate HTML tags and textual words. Then it intelligently assembles them into a special JavaScript program. The latter represents the original HTML code as exactly the same content. However, being a program, this new script has a full control over its elements.
In particular, every word here has unique ID. When you highlight or edit text, you are changing status of the element(s) with a certain ID.

The Builder's complete output is the Tunetext Application, -- a special set of HTML, JavaScript, and image files, which provides all the Tunetext functionality:

In turn, the user's changes form another JavaScript program. It's so tiny that may be saved in a special location on your PC as the Microsoft's Userdata Behaviour.
In the most cases the saving occurs automatically, behind the scene. However, you always can backup it in the form of file (info-Profile).

During loading a page, the TuneText "reads" related script, searches through the page for content with the appropriate IDs, and forms corresponding view.