While it is running, the device continuously prints out a stream of changes like a running receipt. Any text that was removed are printed out in inverted colors while any text added are underlined.
Diff was inspired by the NewsDiffs project, which monitors the various versions of news articles on different websites. According to a post on the NYTLabs blog, the device was conceived as “a hardware experiment that transposed rhythms and signals from the network realm onto the physical world, while remaining a background process that wouldn’t irritate everyone in the Lab.”
The creators decided to use headlines because they provided an easy way to implement and understand what kind of information something like this can give.