it uses the gecko layout engine from the mozilla project to show web pages; however, the epiphany developers have a new but less stable version of epiphany 2.21.4 using the webkit engine instead of gecko. the epiphany team wants to stop using gecko and only use the webkit engine, by the time they release epiphany 2.24 or 2.26. epiphany has tabbed browsing, cookie management, popup blocking and an extensions system. epiphany can be extended with the epiphany-extensions package in gnu/linux operating systems.