Media Queries in Bootstrap allow you to move, show and hide content based on the viewport size. The following media queries are used in LESS files to create the key breakpoints in the Bootstrap grid system:
/* Small devices (tablets, 768px and up) */
@media (min-width: @screen-sm-min) { ... }
/* Medium devices (desktops, 992px and up) */
@media (min-width: @screen-md-min) { ... }
/* Large devices (large desktops, 1200px and up) */
@media (min-width: @screen-lg-min) { ... }
Occasionally these are expanded to include a max-width to limit CSS to a narrower set of devices:
@media (max-width: @screen-xs-max) { ... }
@media (min-width: @screen-sm-min) and (max-width: @screen-sm-max) { ... }
@media (min-width: @screen-md-min) and (max-width: @screen-md-max) { ... }
@media (min-width: @screen-lg-min) { ... }