Apache is a free and open-source cross-platform web server software.
Mod_dav is an Apache module to provide WebDAV capabilities for your Apache web server. It is an open-source module, provided under an Apache-style license.
PHP is a general-purpose scripting language used for web development.
Ubuntu is a free and open-source operating system on Linux for the enterprise server, desktop, cloud, and IoT.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.