The `::before` pseudo-element in CSS is used to insert content before the content of an element. Here is an example of how to use the `::before` pseudo-element:
```
p::before {
content: “Read this -”;
color: red;
}
```
In this example, we are selecting all `
` tags and before the content of each `
` element, we are inserting the text “Read this -” in red color.
So if you had a paragraph:
```
Lorem ipsum dolor sit amet…
After applying the CSS, it would be displayed like this:
```
Read this – Lorem ipsum dolor sit amet…
```
The `content` property is necessary for the `::before` pseudo-element to work. It can contain string, image or nothing.
Because `::before` is a pseudo-element it is not a part of the DOM, so it cannot be manipulated by JavaScript or jQuery. It is also worth noting that pseudo-elements are not recognized in older versions of Internet Explorer (IE8 and below).
