With Bootstrap 4 .hidden-* classes were completely removed. Starting with v4-beta, you can combine .d-*-none and .d-*-block classes to achieve the same result. visible-* was removed as well; instead of using explicit .visible-* classes, make the element visible by not hiding it (again, use combinations of .d-none .d-md-block)
<div class="d-none d-sm-block"> hidden-xs
<div class="d-none d-md-block"> visible-md and up (hidden-sm and down)
<div class="d-none d-lg-block"> visible-lg and up (hidden-md and down)
<div class="d-none d-xl-block"> visible-xl
</div>
</div>
</div>
</div>
<strong>
<div class="d-sm-none"> eXtra Small <576px </div>
<div class="d-none d-sm-block d-md-none d-lg-none d-xl-none"> SMall ≥576px </div>
<div class="d-none d-md-block d-lg-none d-xl-none"> MeDium ≥768px </div>
<div class="d-none d-lg-block d-xl-none"> LarGe ≥992px </div>
<div class="d-none d-xl-block"> eXtra Large ≥1200px </div>
</strong>
<div class="d-xl-none"> hidden-xl (visible-lg and down)
<div class="d-lg-none d-xl-none"> visible-md and down (hidden-lg and up)
<div class="d-md-none d-lg-none d-xl-none"> visible-sm and down (or hidden-md and up)
<div class="d-sm-none"> visible-xs
</div>
</div>
</div>
</div>
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