Are you looking for the Joomla 3 version of Tooltips?
Tooltips is a Joomla! system plugin that allows you to display content when the user moves the mouse pointer over an element, without clicking it (also known as "popovers").
When a user moves their pointer to text, or an image, for which you have defined a tooltip, a small "hover box" appears. This box can contain text or an image. Optionally the text can contain html formatting including URLs.
The syntax simply looks like:
{tip title="Wow!" content="Now I can give something a cool tooltip!"}This text has a tooltip.{/tip}
The result is: This text has a tooltip.
But you can also give tooltips styles, like this. Or even use images in popups:
You can create these tooltips almost anywhere in your site. Not only in articles, but anywhere you can enter text, like in modules and components. The tooltips are fully styleable through settings and CSS.
Note: On touchscreen devices, the tooltips will be triggered by clicking on them.