Chromebooks ship with ChromeOS, an operating system that uses the Linux kernel and the Google Chrome web browser with an integrated media-player.[34][35] Enabling developer mode allows the installation of Linux distributions and other operating systems on Chromebooks. Chromebooks also include a screw or switch directly on the motherboard to enable or disable write protection. Crouton is a script that allows the installation of Linux distributions from ChromeOS and running both operating systems simultaneously.[36] Some Chromebooks include SeaBIOS, which can be enabled to install and boot Linux distributions directly.[37][38] With limited offline capability and a fast boot-time, Chromebooks are primarily designed for use while connected to the Internet[39] and signed in to a Google account.[40] Instead of installing traditional applications that propose risk of malware, users install web apps from the Chrome Web Store.[41] Google claims that a multi-layer security architecture eliminates the need for anti-virus software.[5]