CSS specificity determines which CSS rule is applied when multiple rules target the same elements. For example, there is a div that has the content "Hello World", we will set a background color to that div. We can set background color in many ways.

• Inline style
• Id selector
• class selector, attribute sector, pseudo selector
• Element selector

Each way has its specificity hierarchy,

Inline Style: The inline style has the highest specificity and overrides all other styles. For example
<div style="background-color: red">Hello World</div>

Id selector: The id selector has less specificity than the inline style and higher specificity than the class selector and element selector
<div id="box1">Hello World</div>
// in CSS file or style in head
#box1{
background-color: red;
}

Class Selector: class selector, attribute selector has medium specificity: for example:
<div class="box">Hello World</div>
// in CSS file or style in head
.box{
background-color: red;
}

Element Selector: Element selector has low specificity, for example:
<div>Hello World</div>
// in CSS file or style in head
div{
background-color: red;
}


There is an exception: If we use !important, it will override all CSS