The .badge class is used to add additional information to the content. For example, some websites associate a number of notifications to the link. The notification number is seen when logged in to a particular website which tells the numbers of news or notifications to see by clicking it.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Badges</title>
<meta charset="utf-8">
<meta name="viewport"
content="width=device-width, initial-scale=1">
<link rel="stylesheet" href=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>
<script src=
"https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js">
</script>
<script src=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js">
</script>
</head>
<body>
<h1 style="color:green;text-align:center;">
GeeksforGeeks
</h1>
<div class="container">
<h4>Notifications heading
<span class="badge badge-secondary">
4
</span>
</h4>
<h4>Updates
<span class="badge badge-secondary">
2
</span>
</h4>
<h4>Messages
<span class="badge badge-secondary">
1
</span>
</h4>
<h4>Request
<span class="badge badge-secondary">
0
</span>
</h4>
</div>
</body>
</html>
Output:

Contextual Badges: The contextual classes (.badge-*) is used to change the color of badges. Badges can be used as part of links or button to provide a counter. Depending on how they used, badges must be confusing for the users. For this purpose different color of variations are used so that the user may not get confused.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Badges</title>
<meta charset="utf-8">
<meta name="viewport"
content="width=device-width, initial-scale=1">
<link rel="stylesheet" href=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>
<script src=
"https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js">
</script>
<script src=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js">
</script>
</head>
<body>
<h1 style="color:green;text-align:center;">
GeeksforGeeks
</h1>
<div class="container">
<h4>Notifications heading
<span class="badge badge-primary">
4
</span>
</h4>
<h4>Updates
<span class="badge badge-warning">
2
</span>
</h4>
<h4>Messages
<span class="badge badge-success">
1
</span>
</h4>
<h4>Request
<span class="badge badge-danger">
0
</span>
</h4>
</div>
</body>
</html>
Output:

Pill Badges: The .badge-pill class is used to make badges corner more rounded.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Badges</title>
<meta charset="utf-8">
<meta name="viewport"
content="width=device-width, initial-scale=1">
<link rel="stylesheet" href=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>
<script src=
"https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js">
</script>
<script src=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js">
</script>
</head>
<body>
<h1 style="color:green;text-align:center;">
GeeksforGeeks
</h1>
<div class="container">
<h4>Notifications heading
<span class="badge badge-primary badge-pill">
4
</span>
</h4>
<h4>Updates
<span class="badge badge-warning badge-pill">
2
</span>
</h4>
<h4>Messages
<span class="badge badge-success badge-pill">
1
</span>
</h4>
<h4>Request
<span class="badge badge-danger badge-pill">
0
</span>
</h4>
</div>
</body>
</html>
Output:

Badge inside an Element: Badges can be created inside an element.
Example:
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Badges</title>
<meta charset="utf-8">
<meta name="viewport"
content="width=device-width, initial-scale=1">
<link rel="stylesheet" href=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
<script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js">
</script>
<script src=
"https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js">
</script>
<script src=
"https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js">
</script>
</head>
<body>
<h1 style="color:green;text-align:center;">
GeeksforGeeks
</h1>
<div class="container">
<button type="button" class="btn btn-primary">
<h4>Notifications heading
<span class="badge badge-primary badge-danger">4</span>
</h4>
</button><br><br>
<button type="button" class="btn btn-warning">
<h4>Updates
<span class="badge badge-light">2</span>
</h4>
</button><br><br>
<button type="button" class="btn btn-primary">
<h4>Messages
<span class="badge badge-success">1</span>
</h4>
</button><br><br>
<button type="button" class="btn btn-danger">
<h4>Request
<span class="badge badge-primary">0</span>
</h4>
</button>
</div>
</body>
</html>
Output:

Supported Browsers:
- Google Chrome
- Internet Explorer
- Firefox
- Opera
- Safari