To build a dismissal alert −

☛ Add a basic alert by creating a wrapper <div> and adding a class of .alert and one of the four contextual classes (e.g., .alert-success, .alert-info, .alert-warning, .alert-danger).

☛ Also add optional .alert-dismissable to the above <div> class.

☛ Add a close button.

☛ Use the <button> element with the data-dismiss = "alert" data attribute.