Marionette [ ˌmarɪəˈnɛt] is
* a puppet worked by strings: the bird bobs up and down like
* a person who is easily manipulated or controlled: many officers
dismissed him as the mayor’s marionette;
* the remote protocol that lets out-of-process programs communicate
with, instrument, and control Gecko-based browsers.
Marionette provides interfaces for interacting with both the internal
as Firefox and Fennec. It can control both the chrome- and content
documents, giving a high level of control and ability to replicate,
or emulate, user interaction.
Head on to the Marionette documentation to find out more: