This is a simplified explanation of what HTML and JavaScript are. It is concise and brief to avoid hitting you with too much geek speak..
HTML is a "markup language" that works much like MS Word and other markup software. Little tags surround content telling it how to appear. Your browser reads those tags and presents a result.
JavaScript is, "a script language - a system of programming codes." These codes allow web masters to add functionality to their site, in other words, do something more than just read the content. Programmers can design functions that alter the results in a web browser. Some people use JavaScript to build menus on their site. There are many uses for it.
Although JavaScript can add some awesome functionality, beware that it may be difficult to program in. Different browsers (i.e. Internet Explorer, Fire Fox, NetScape, etc.) handle functions differently and sometimes to get a function to work a programmer has to write it multiple times in multiple ways to handle browser differences.
We recommend that if typical site owners want to use JavaScript to enhance a site that they hire out the programming or find the script already done and free for licensing on the net.
Here are some sites to find cool scripts: