This is the text that is presented as a 'ToolTip' when the mouse rolls onto an object and pauses there for a few moments. The MSIE browser and the Netscape 6.0 browser will display this text as a small popup comment box. Earlier versions of Netscape prior to version 6.0 did not support this capability, so it should be considered somewhat implementation-dependent until the penetration of newer browsers increases.
When aural style sheet support is provided by a browser, this value might be spoken as the mouse rolls over it.
This property is not the name of the object. The ID tag attribute is a more reliable way of making that association, since it assists with the document.all array construction and indexing on MSIE, and is more portable across browsers when accessing objects associatively.
Another recommended technique is the DOM compliant getElementById() method which in the longer term will become more prevalent.
This is also not the same as the altText on an image, which may also appear as a ToolTip in some browsers.