BEM (Block, Element, Modifier) is a CSS methodology developed in 2009 by Yandex (think of them as Russia’s Google).
CSS is one of the easiest programming language but very hard to maintain. Using IDs and !important in your CSS will lead to chaos in the future, especially when your project gets bigger and starts having more people in your development team.
BEM CSS methodology simply fixes this problem and provides a better structure for your CSS code and scalable CSS!
Let’s build a card component;
.cardis a block that contains all elements.
I suggest everyone uses BEM, it's my favourite CSS naming scheme. By using BEM, updating CSS codes and/or adding new codes with no conflict is so fast and easy.