Apache is a free and open-source cross-platform web server software.
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.
Unix is a family of multitasking, multiuser computer operating systems.
WordPress is a free and open-source content management system written in PHP and paired with a MySQL or MariaDB database. Features include a plugin architecture and a template system.