Tooltip

The tooltip, also known as infotip or hint, is a common graphical user interface element in which, when hovering over a screen element or component, a text box displays information about that element (such as a description of a button's function, or what an abbreviation stands for). The tooltip is displayed continuously as long as the user hovers over the element.
On desktop, it is used in conjunction with a cursor, usually a pointer, whereby the tooltip appears when a user hovers the pointer over an item without clicking it. 
On mobile operating systems, a tooltip is displayed upon long-pressing—i.e., tapping and holding—an element. Some smartphones have alternative input methods such as a stylus, which can show tooltips when hovering above the screen.
A common variant of tooltips, especially in older software, is displaying a description of the tool in a status bar. Microsoft's tooltips feature found in its end-user documentation is named ScreenTips. The classic Mac Operating System uses a tooltips feature, though in a slightly different way, known as balloon help. Some software and applications, such as GIMP, provide an option for users to turn off some or all tooltips. However, such options are left to the discretion of the developer, and are often not implemented.
Origin.
The term "tooltip" originally came from older Microsoft applications (e.g., Microsoft Word 95). These applications would have toolbars wherein, when moving the mouse over the Toolbar icons, displayed a short description of the function of the tool in the toolbar. More recently, these tooltips are used in various parts of an interface, not only on toolbars.
Examples.
CSS, HTML, and JavaScript also other coding systems allow web designers to create customized tooltips.
Demonstrations of tooltip usage are prevalent on web pages. Many graphical web browsers display the codice_1 attribute of an HTML element as a tooltip when a user hovers the pointer over that element; in such a browser, when hovering over Wikipedia images and hyperlinks a tooltip will appear.
The codice_2 template is an example of using tooltip inside Wikipedia, wherein the template shows the tooltip and the text. Another method is to use .