Marionette [ ˌmarɪəˈnɛt] is * a puppet worked by strings: the bird bobs up and down like a marionette; * 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 JavaScript runtime and UI elements of Gecko-based browsers, such 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: https://firefox-source-docs.mozilla.org/testing/marionette/marionette/