This is using the :hover pseudoelement in CSS3.
HTML:
<div id="wrapper">
<img src="http://placehold.it/300x200" class="hover" />
<p class="text">text</p>
</div>
CSS:
#wrapper .text {
position:relative;
bottom:30px;
left:0px;
visibility:hidden;
}
#wrapper:hover .text {
visibility:visible;
}
Demo HERE.
This instead is a way of achieving the same result by using jquery:
HTML:
<div id="wrapper">
<img src="http://placehold.it/300x200" class="hover" />
<p class="text">text</p>
</div>
CSS:
#wrapper p {
position:relative;
bottom:30px;
left:0px;
visibility:hidden;
}
jquery code:
$('.hover').mouseover(function() {
$('.text').css("visibility","visible");
});
$('.hover').mouseout(function() {
$('.text').css("visibility","hidden");
});
You can put the jquery code where you want, in the body of the HTML page, then you need to include the jquery library in the head like this:
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
</head>
You can see the demo HERE.
When you want to use it on your website, just change the <img src /> value and you can add multiple images and captions, just copy the format i used: insert image with class="hover" and p with class="text"