Apache is a free and open-source cross-platform web server software.
Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
PHP is a general-purpose scripting language used for web development.
Priority Hints exposes a mechanism for developers to signal a relative priority for browsers to consider when fetching resources.
Unix is a family of multitasking, multiuser computer operating systems.