HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
MailChimp for WordPress is an email marketing plugin that enables you to build subscriber lists.
Open Graph is a protocol that is used to integrate any web page into the social graph.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
PHP is a general-purpose scripting language used for web development.
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.
Yoast SEO is a search engine optimisation plugin for WordPress and other platforms.