Every web developer, designer or manager who supports huge project or tries to reuse some parts of HTML + CSS anywhere else sooner or later will face with the same issues and most likely come to the idea of componentized web. It's rather popular now and was even described as a W3C standard Web Components. But how exactly new are the new ideas and how useful is its realization? In the frontend world since Internet Explorer 5.5 a lot of developers know and use BEM methodology that was created to solve exactly the same problems. During years of use it formed its own huge ecosystem that includes technologies, tools, libraries and active community. It is built and developed by developers within Yandex and outside that use it everywhere both in small such as promo page for a cat and high loaded projects such as Yandex services and Mail.ru. They are well aware of the problems that developers face.