Varvara Stepanova presents BEM methodology and tools.
BEM stans for "Block Element Modifier".
First, it is a methodology, a way of thinking when developing web interface applicable for any technology.
Besides, BEM is a range of tools to automate developer's work and to optimase code for production.
Finnally, BEM is a bunch of interface libraries helping developers to make their work faster and better.
Informal video: https://vimeo.com/53219242