BEM (Block, Element, Modifier) is a naming convention for classes in HTML and CSS what was developed by Yandex.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
PHP is a general-purpose scripting language used for web development.
A modest JavaScript framework for the HTML you already have.
VK is a Russian online social media and social networking service.