Header Footer Code Manager by Draftpress is a easy interface to add snippets to the header or footer or above or below the content of your page.
Facebook pixel is an analytics tool that allows you to measure the effectiveness of your advertising.
Open Graph is a protocol that is used to integrate any web page into the social graph.
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.
WP Rocket is a caching and performance optimisation plugin to improve the loading speed of WordPress websites.
Yoast SEO is a search engine optimisation plugin for WordPress and other platforms.