HTML 5 (HyperText Markup Language) is a markup language used for structuring and presenting content on the World Wide Web.
CSS (Cascading Style Sheets) is a style sheet language used for describing the presentation of a document written in HTML.
PHP is a server side scripting language for Web development, but also used as a general-purpose programming language.
Bootstrap is a free and open-source front-end framework for designing websites and it concerns itself with front-end development only.
WordPress is a open-source content management system (CMS) based on PHP and MySQL. Features include a plugins and a template system.