As an example, in a typical sentence, such as "There are 3400 calories in a pound of bodyfat" a website visitor would be able to change the calories to 3500, which is the correct number. The numbers are not the point, being able to change the text is what counts--any text that is specified as being interactive would be able to be edited by the user.
The same concept could be used to grab info from a Wikipedia page, for instance, without leaving the page. The Tangle API is still in alpha stage, and is a great initial step towards interactive web-based text besides the normal hyperlink experience, which is about as interactive as text is with normal HTML (HTML5 has some interactive functionality, but Tangle takes it a few steps further).
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