This text is hidden on an EXTRA SMALL screen.

This text is hidden on a SMALL screen.

This is text hidden on a MEDIUM screen.

This is text hidden on a LARGE screen.

The .show class forces an element to be shown (display:block):

This paragraph is forced to be shown (display:block).

The .hidden class forces an element to be hidden (display:none):

This paragraph is forced to be hidden (display:none).

The .invisible class makes an element invisible (visibility:hidden) - will take up space on page:

This paragraph is forced to be hidden (visibility:hidden).

Sample text to show elements with class="invisible" takes up space.

Remember that extra-small/mobile (formerly xs) is the default (implied) breakpoint, unless overridden by a larger breakpoint. Therefore, the -xs infix no longer exists in Bootstrap 4. Show/hide for breakpoint and down: hidden-xs-down (hidden-xs) = d-none d-sm-block
hidden-sm-down (hidden-sm hidden-xs) = d-none d-md-block
hidden-md-down (hidden-md hidden-sm hidden-xs) = d-none d-lg-block
hidden-lg-down = d-none d-xl-block
hidden-xl-down (n/a 3.x) = d-none (same as hidden)

Show/hide for breakpoint and up: hidden-xs-up = d-none (same as hidden)
hidden-sm-up = d-sm-none
hidden-md-up = d-md-none
hidden-lg-up = d-lg-none
hidden-xl-up (n/a 3.x) = d-xl-none
Show/hide only for a single breakpoint:

hidden-xs (only) = d-none d-sm-block (same as hidden-xs-down)
hidden-sm (only) = d-block d-sm-none d-md-block
hidden-md (only) = d-block d-md-none d-lg-block
hidden-lg (only) = d-block d-lg-none d-xl-block
hidden-xl (n/a 3.x) = d-block d-xl-none
visible-xs (only) = d-block d-sm-none
visible-sm (only) = d-none d-sm-block d-md-none
visible-md (only) = d-none d-md-block d-lg-none
visible-lg (only) = d-none d-lg-block d-xl-none
visible-xl (n/a 3.x) = d-none d-xl-block

---