Bootstrap 4
Bootstrap 4 Colors
The bootstrap 4 colors are mainly three ( Text Colors, Link Colors, Background Colors). The color classes are : .text-primary, .text-success, .text-info, .text-warning, .text-danger.text-light ,  .text-dark,  .text-white ,  .text-secondary  and .text-muted   :
<p class="text-primary">Free Time Learning (.text-primary)</p>
<p class="text-success">Free Time Learning (.text-success)</p>
<p class="text-info">Free Time Learning (.text-info)</p>
<p class="text-warning">Free Time Learning (.text-warning)</p>
<p class="text-danger">Free Time Learning (.text-danger)</p>
<p class="text-light">Free Time Learning (.text-light)</p>
<p class="text-dark">Free Time Learning (.text-dark)</p>
<p class="text-white">Free Time Learning (.text-white)</p>
<p class="text-secondary">Free Time Learning (.text-secondary)</p>
<p class="text-muted">Free Time Learning (.text-muted)</p>
Output :
Text Links

Contextual text classes can also be used on links, which will add a darker hover color.

Note: .text-white and .text-muted class has no link styling.

<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-primary">www.freetimelearning.com (.text-primary)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-success">www.freetimelearning.com (.text-success)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-info">www.freetimelearning.com (.text-info)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-warning">www.freetimelearning.com  (.text-warning)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-danger">www.freetimelearning.com (.text-danger)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-light">www.freetimelearning.com (.text-light)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-dark">www.freetimelearning.com (.text-dark)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-white">www.freetimelearning.com (.text-white)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-secondary">www.freetimelearning.com (.text-secondary)</a></p>
<p><a href="http://www.freetimelearning.com/" target="_blank" class="text-muted">www.freetimelearning.com (.text-muted)</a></p>
Output :
Background Colors

The Bootstrap 4 background colors are : .bg-primary, .bg-success, .bg-info, .bg-warning, .bg-danger.bg-light.bg-dark.bg-white ,  .bg-secondary  and .bg-muted   :

<p class="p-3 mb-2 bg-primary text-white">Free Time Learning (.text-primary)</p>
<p class="p-3 mb-2 bg-success text-white">Free Time Learning (.text-success)</p>
<p class="p-3 mb-2 bg-info text-white">Free Time Learning (.text-info)</p>
<p class="p-3 mb-2 bg-warning text-white">Free Time Learning (.text-warning)</p>
<p class="p-3 mb-2 bg-danger text-white">Free Time Learning (.text-danger)</p>
<p class="p-3 mb-2 bg-light text-dark">Free Time Learning (.text-light)</p>
<p class="p-3 mb-2 bg-dark text-white">Free Time Learning (.text-dark)</p>
<p class="p-3 mb-2 bg-white text-dark">Free Time Learning (.text-white)</p>
<p class="p-3 mb-2 bg-secondary text-white">Free Time Learning (.text-secondary)</p>
<p class="p-3 mb-2 bg-muted text-dark">Free Time Learning (.text-muted)</p>
Output :