I have a couple of clarifications to add here:
1) The list shown (visible-phone, visible-tablet, etc.) is deprecated in Bootstrap 3. The new values are:
The asterisk translates to the following for each (I show only visible-xs-* below):
2) When you use these classes, you don't add a period in front (as confusingly shown in part of the answer above).
For example:
<div class="visible-md-block col-md-6 text-right text-muted">
<h5>Copyright © 2014 Jazimov</h5>
</div>
3) You can use visible-* and hidden-* (for example, visible-xs and hidden-xs) but these have been deprecated in Bootstrap 3.2.0.
For more details and the latest specs, go here and search for "visible": http://getbootstrap.com/css/