How to implement Headless Testing or Run Selenium Scripts in Headless Mode 2022

What is a headless browser / Mode?
A headless browser is a state to define browser simulation programs that do not have a GUI representation. It works like any other browser but does not present any UI(user interface). In headless mode, when Selenium tests run, they execute in the background. Finally, almost every modern browser allows its users to run their browser in headless mode.