<noscript> - The <noscript> tag is used to define an alternate content for browsers where scripts are disabled or does not support scripts.
Note:- In HTML 4.01 The <noscript> tag is used only within <body> tag. But in HTML5 it can used within both <head> and <body> tag. In XHTML not support the <noscript> tag.
<applet> - The <applet> tag is used to define an embedded applet. Applet is a java program for web.
NOTE:- HTML5 does not support <applet>.
<title>The Hello, World Applet</title>
<hr> <applet code = "HelloWorldApplet.class" width = "360" height = "200"> If your browser was Java-enabled, a "Hello, World"
message would appear here. </applet>
<embed> - The <embed> tag is used as container for an external application or interactive content, like flash animation. It is new in HTML5 but not supported in HTML 4.