bootstrap 4 icons
snippet in html

bootstrap 4 icons

user6554


<link rel="stylesheet" 
 	href="https://use.fontawesome.com/releases/v5.7.0/css/all.css" 
  	integrity="sha384-lZN37f5QGtY3VHgisS14W3ExzMWZxybE1SJSEsQp9S+oqd12jhcu+A56Ebc1zFSJ" 
    crossorigin="anonymous"> 
     
<i class="fas fa-cloud"></i>
<i class="fas fa-coffee"></i>
<i class="fas fa-car"></i>
<i class="fas fa-file"></i>
<i class="fas fa-bars"></i>

glyphicon in bootstrap 4.4

user4793

<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet">

bootsrap updateicon

user8360

<i class="fa fa-refresh" aria-hidden="true"></i>

boostrap icons

user6754

Bootstrap 4 does not have its own icon library (Glyphicons from Bootstrap 3 are not supported in BS4). However, there are many free icon libraries to choose from, such as Font Awesome and Google Material Design Icons.

To use Font Awesome icons, add the following to your HTML page (No downloading or installation is required):

     <link rel="stylesheet" 
     href="https://use.fontawesome.com/releases/v5.7.0/css/all.css" 
     integrity="sha384-lZN37f5QGtY3VHgisS14W3ExzMWZxybE1SJSEsQp9S+oqd12jhcu+A56Ebc1zFSJ" 
     crossorigin="anonymous">