Alt Tags in Firefox - Don't Display

I am wondering how to do this -

In IE, the alt tags of my images appear just fine when hovering or the image doesn't show. However, when testing in Firefox/Safari, the alt tags don't show. Here is a typical line I'd use for my img

<img src="img/img.jpg" class ="blueborder" width="128" height="96" alt="image deciption in here" />

Does anyone know how I can code this to make the alt tags work in other browsers please?

Many thanks for any help

If you want tool-tips, you need to use the "title" attribute. I always use both "alt" and "title".

Most web browsers other than IE rely on the title tag for the hovering text display:

<img src="img/img.jpg" class ="blueborder" width="128" height="96" alt="image deciption in here" title="image deciption in here" />

Yeah, the alt tag is only for when the browser is set not to display images or the images don't load.

thanks to ebveryone for their help. I now have it working as it should.