Currently, my webpage images use the alt attribute only.
Users complain that their IE8 cannot show the "tooltip" bubble when they mouse over the image. On Microsoft's What's New in Internet Explorer 8 page, it says
The alt attribute is no longer displayed as the image tooltip when the browser is running in IE8 Standards mode. Instead, the target of the longDesc attribute is used as the tooltip if present; otherwise, the title is displayed. The alt attribute is still used as the Microsoft Active Accessibility name, and the title attribute is used as the fallback name only if alt is not present.
I also found that many say title should be used.
Which should I use to meet the industrial standard: alt, longdesc or title?