Apache is a free and open-source cross-platform web server software.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
OpenSSL is a software library for applications that secure communications over computer networks against eavesdropping or need to identify the party at the other end.
Unix is a family of multitasking, multiuser computer operating systems.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.