What are the most frequently used CSS selector?

The most frequently used CSS selector are:

1. Element selector (HTML tag selector)
2. Class selector 
3. ID selector    

Element selector (HTML tag selector):

<div class="first" id="first">First content</div>

<style>

div{

   background-color:blue;

}

</style>

Class selector:

<div class="first" id="first">First content</div>

<style>

.first{

   background-color:blue;

}

</style>

ID selector:

<div class="first" id="thisID">First content</div>

<style>

#thisID{

   background-color:blue;

}

</style>