Javascript

To identify Javascript inline:

<script type="text/javascript">
</script>

or externally:

<script type="text/javascript">
</script>

To output text:

document.write("stuff")

To create i/o message boxes:

alert("alert text") // Waits for OK
confirm("confirmation text") // Waits for OK (true) or Cancel (false)
prompt("prompt text","default value") // Waits for value to be etnered