BEM stands for Block, Element, Modifier, a CSS naming convention that improves code maintainability and scalability. 1. Block is a standalone component like .button or .card. 2. Element is a part of a block, named as block__element, such as .card__title. 3. Modifier is a flag for changes in state or appearance, formatted as block--modifier or block__element--modifier, like .button--primary. It provides clear structure, avoids specificity issues, reduces naming conflicts, and enhances team collaboration. Example:
Welcome
This is a sample card.
BEM stands for Block, Element, Modifier — it's a popular naming convention in CSS that helps developers write more maintainable and scalable code, especially in large projects. The main idea behind BEM is to break the user interface into independent, reusable components (blocks), making styles less fragile and easier to understand.

Here’s how it works:
? Block
A standalone, reusable component that has meaning on its own. It represents a high-level component like a button, menu, or form.

Example:
.card { } .button { } .header { }
? Element
A part of a block that can't be used separately from it. Elements are semantically tied to their block. The naming format is: block__element
.

Example:
.card__title { } .card__body { } .button__text { }
This makes it clear that .card__title
is a child part of the .card
block.
? Modifier
A flag used to change the appearance, behavior, or state of a block or element. It uses the format: block--modifier
or block__element--modifier
.
Example:
.button--primary { } .button--large { } .card--highlighted { }
This tells you that it’s a variation of the base block.
? Why Use BEM?
- Clear structure: You can instantly tell how elements relate to each other.
- Avoids specificity issues: Since BEM uses flat, single classes, it reduces the need for deep nesting.
- Reduces naming conflicts: The unique naming pattern prevents accidental style overrides.
- Team-friendly: Makes collaboration easier because the naming is self-documenting.
? Example in HTML & CSS
<div class="card card--featured"> <h2 class="card__title">Welcome</h2> <p class="card__description">This is a sample card.</p> <button class="button button--primary">Click Me</button> </div>
.card { /* base styles */ } .card--featured { /* featured variation */ } .card__title { /* title inside card */ } .card__description { /* description inside card */ } .button { /* base button */ } .button--primary { /* primary style for button */ }
?? Common Pitfalls to Avoid
- Don’t over-nest: BEM discourages deep nesting like
.card__title--important
. - Don’t create elements of elements: Avoid things like
card__title__highlight
. - Keep blocks independent: A block should ideally work anywhere, not rely on context.
BEM might feel verbose at first, but it pays off in larger projects where clarity and maintainability matter. It’s widely used in big companies and frameworks because it scales well.
Basically, if you want to write CSS that’s easier to debug, reuse, and collaborate on — BEM is a solid choice.
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