Summary  
This chapter covers using CSS pseudo-elements (::before and ::after) to insert decorative content and effects around elements without altering the HTML.  

General domain of usage  
Web user interface styling (e.g., enhancing navigation link hover effects)

Pseudo-elements `::before` and `::after` are special selectors that allow us to insert content before or after an element's content. We use them to add decorative elements, such as icons or borders, to an element's content without modifying the actual HTML content.
```css
selector::before {
  /* some properties */
}

selector::after {
  /* some properties */
}
```
- `::before` adds the content before the element content;
- `::after` adds the content after the element content.

Let's consider the following example, where our task is to add some decoration for the hover effect on the links:

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Creating Effects with Decorative Pseudo-Elements

Creating Effects with Decorative Pseudo-Elements