Different types of predefined button in Bootstraps ?

Answer:

We have some predefined types of buttons such as primary, success, warning, danger and info which are of different types in terms of colors.
Here are shown in the example

<div>

     <button type="button" class="btn btn-default">Default</button>

     <button type="button" class="btn btn-primary">Primary</button>

     <button type="button" class="btn btn-warning">Warning</button>

     <button type="button" class="btn btn-success">Success</button>

     <button type="button" class="btn btn-info">Info</button>

     <button type="button" class="btn btn-danger">Danger</button>

     <button type="button" class="btn btn-link">Link Button</button>

 </div> 

These are visible with different colors in the browser.