btn default class in bootstrap 4

1<button type="button" class="btn btn-primary">Blue</button>
2<button type="button" class="btn btn-secondary">Grey</button>
3<button type="button" class="btn btn-success">Green</button>
4<button type="button" class="btn btn-danger">Red</button>
5<button type="button" class="btn btn-warning">Yellow</button>
6<button type="button" class="btn btn-info">Ligth blue</button>
7<button type="button" class="btn btn-light">White</button>
8<button type="button" class="btn btn-dark">Black</button>
9
10<button type="button" class="btn btn-link">White with blue text</button>

1<button type="button" class="btn btn-primary">Primary</button>
2<button type="button" class="btn btn-secondary">Secondary</button>
3<button type="button" class="btn btn-success">Success</button>
4<button type="button" class="btn btn-danger">Danger</button>
5<button type="button" class="btn btn-warning">Warning</button>
6<button type="button" class="btn btn-info">Info</button>
7<button type="button" class="btn btn-light">Light</button>
8<button type="button" class="btn btn-dark">Dark</button>
9
10<button type="button" class="btn btn-link">Link</button>

1<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
2
3<div class="container m-3">
4    <a class="btn btn-outline-secondary">outline-secondary link</a>
5    <button type="button" class="btn btn-outline-secondary">outline-secondary 'button'</button>
6    <br><br>
7    <a class="btn btn-outline-light">outline-light link</a>
8    <button type="button" class="btn btn-outline-light">outline-light 'button'</button>
9</div>