"A headless browser is a web browser without a graphical user interface.

Headless browsers provide automated control of a web page in an environment similar to popular web browsers, but they are executed via a command-line interface or using network communication. They are particularly useful for testing web pages as they are able to render and understand HTML the same way a browser would, including styling elements such as page layout, colour, font selection and execution of JavaScript and Ajax which are usually not available when using other testing methods.^[1]

Since version 59 of Google Chrome^[2][3] and version 56^[4] of Firefox,^[5] there is native support for remote control of the browser. This made earlier efforts obsolete, notably PhantomJS.^{[6] [...] "}

Cyt. Wikipedia  https://en.wikipedia.org/wiki/Headless_browser