HTML Scripts - W3school | Tutorialspoint

HTML Scripts gives us way to embed or include client side script into the HTML Document. HTML script (<script>…</script>) tag is used to include a block of client side script or to call it from external source.

Internal Script-

You can define your custom block or function of client side scripting language inside a HTML Document itself.

Example:

<script type="text/javascript">
   document.write("Hello Javascript!")
</script>

External Script-

If you have ready to use client side script library or custom script that you want to reuse then you can call into the HTML Document.

Example:

<script src="custom.js" type="text/javascript" />