.align-baseline, .align-top, .align-middle, .align-bottom, .align-text-top and .align-text-bottom set vertical-align, which affects only inline, inline-block, inline-table and table-cell elements. Use them to line up an icon <img> with the text beside it, or put .align-middle on a .table or <tr> to center every cell's content vertically. They do nothing to block or flex items; center those with .align-items-center on the flex container.