Alerts are good for bringing attention to something like an notice or some sort of warning.

<div class="alert alert-primary">
  This is a primary alert—check it out!
</div>
<div class="alert alert-secondary">
  This is a secondary alert—check it out!
</div>
<div class="alert alert-success">
  This is a success alert—check it out!
</div>
<div class="alert alert-danger">
  This is a danger alert—check it out!
</div>
<div class="alert alert-warning">
  This is a warning alert—check it out!
</div>
<div class="alert alert-info">
  This is a info alert—check it out!
</div>
<div class="alert alert-light">
  This is a light alert—check it out!
</div>
<div class="alert alert-dark">
  This is a dark alert—check it out!
</div>
This is a primary alert—check it out!
This is a secondary alert—check it out!
This is a success alert—check it out!
This is a danger alert—check it out!
This is a warning alert—check it out!
This is a info alert—check it out!
This is a light alert—check it out!
This is a dark alert—check it out!