From MozillaZine Knowledge Base

Microsoft Internet Explorer (4.0 and above, Windows-only) supports a proprietary extension to CSS called “filters.” One of these filters is the glow filter. It renders a blurred radiance around an object (or text) so that it appears to glow.

IE’s filter syntax will never be implemented in Mozilla, for a variety of reasons:

• filter is not defined in the CSS specifications
• The syntax is technically reserved for possible future use, as it is not formatted as a vendor-specific extension
• The CSS3 feature text-shadow, currently being specified, will offer the same functionality as Microsoft’s glow filter in a standard-compliant form.

Those interested in this functionality may want to watch bug 10713.

External links

• Bug 10713 - Implement CSS2/3 text-shadow property
• Bug 64019 - implement the filter: style rule (css) (WONTFIX)
• CSS: text shadows