That’s maybe an old tip and probably everybody already knows it, but because I just answered that question on the OraFAQ forum, I wanted to share it with you in case you didn’t know.
Maybe you have already noticed that in the Oracle APEX Builder at some pages a tooltip is used. For example for the icons on the Drag and Drop Layout page. This tooltip functionality can be reused in your own applications. You just have to add
onmouseover="toolTip_enable(event,this,'This is a tooltip')"
into the “Attributes” property of your HTML button or into the “HTML Form Element Attributes” property of your page item. In the end you can attach it to any HTML element. But I think you got the idea how it works.