• HTML comments with special syntax recognized only by Microsoft Internet Explorer versions 5 through 9, allowing developers to target IE-specific code or provide fallbacks for IE’s non-standard behavior. The syntax used patterns like <!--[if IE]> or <!--[if lt IE 9]> to conditionally include CSS, JavaScript, or HTML based on the IE version, with the content appearing as regular comments to other browsers. Microsoft discontinued support for Conditional Comments in Internet Explorer 10 and later, encouraging developers to use feature detection and standards-compliant code instead.

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