a visually hidden button e.g fontawesome button
<button>
<span class="visually-hidden">Help!</span> <!-- add visually hidden for screen readers -->
<i class="icon icon-help" aria-hidden="true"></i><!-- add aria-hidden true -->
</button>
<script><
/** from html5 boilerplate */
.visually-hidden {
border: 0;
clip: rect{0,0,0,0);
height: 1px;
margin: -1px;
overflow: hidden;
padding: 0;
position: absolute;
width: 1px;
}
</script?