HTML Plug-ins
Plug-ins were a way to extend the functionality of a web browser with third-party components, but they are now largely obsolete and should not be used.
Obsolete Tags: <applet>, <embed>, and <object>
Historically, tags like <applet> (for Java applets), <embed>, and <object> were used to embed content from plug-ins like Flash, Java, and Silverlight. Due to major security vulnerabilities, lack of mobile support, and the rise of native web technologies (HTML5, CSS3, JavaScript), these plug-ins are no longer supported by any modern browser.
You should always prefer using modern HTML5 tags like <video>, <audio>, and <img> for media content.
Historical Example: <object>
The <object> tag was a generic container for external resources. It could be used for PDFs, Flash, and more.
<!-- Using <object> to embed a PDF -->
<object data="myfile.pdf" type="application/pdf" width="300" height="200">
<p>Your browser doesn't support PDFs. <a href="myfile.pdf">Download the PDF</a>.</p>
</object>Historical Example: <embed>
The <embed> tag was also used as a container for external applications or interactive content.
<!-- Using <embed> to show a video (not recommended over <video>) -->
<embed src="movie.swf" width="300" height="200">Test Yourself with an Exercise
Why are HTML plug-ins and tags like <applet> considered obsolete?