onBlur
The instruction(s) to be executed are placed within quotes. This event handler will execute the instruction(s) when the object it has been assigned to loses 'focus', or becomes 'blurred'. For example, when a cell of a table has been made active by either clicking on it or tabbing to it, you've satisfied its 'focus'. When you move the 'focus' away, that cell has become 'blurred'.

The following example will display text of your choosing in a message box when the object assigned becomes 'blurred':
onBlur="msgWindow.document.write('-- Insert text message here --')"
This Event Handler is used with the following:

A
APPLET
AREA
BUTTON
CAPTION
DIV
EMBED
FIELDSET
IMG
LEGEND
MARQUEE
OBJECT
SELECT
SPAN
TABLE
TD
TEXTAREA
TH
TR