You are free to embed as many scripts into a single document as you like, using multiple SCRIPT tags. A script embedded in HTML with the SCRIPT tag uses the format:

<script language="JavaScript"> <!-- document.write("Hello World!"); //--> </script>

The LANGUAGE attribute is optional, but recommended. You may specify that a section of code only be executed by browsers which support a particular version of JavaScript; for instance:

<script language="JavaScript1.2">

Another attribute of the SCRIPT tag, SRC, can be used to include an external file containing JavaScript code rather than code embedded into the HTML:

<script language="JavaScript" src="corefunctions.js"> </script>

The external file is simply a text file containing JavaScript code, and whose filename ends with the extension ".js". Note that although some version 3 browsers support the SRC attribute, it only functions reliably across platforms in the version 4 browsers.

Scripts can be placed inside comment fields to ensure that your JavaScript code is not displayed by old browsers that do not recognize JavaScript. The markup to begin a comment field is <!-- while you close a comment field using //-->. This practice is certainly optional, but considered good form when your page is likely to be visited by older browsers. Certainly, as older browsers fade away, this practice will likely become unnecessary.