HTML per-se (without JavaScript) is a static language, which means that you cannot query databases, send e-mails, execute searches, or generally interact with the server, and return dynamic results to the user.
Imagine that you need to do one of the above tasks. HTML doesn't offer any solutions for these kinds of problems because it is just a way to display information and not manipulate other systems.
What can we do in order to overcome this problem?
ColdFusion Markup Language (CFML) neatly fits into the HTML syntax and allows you to place CFML tags in-between HTML tags. Basically, Railo Server generates HTML, which is then interpreted by the browser.
Depending on the tags that you are using, different HTML pages are sent back to the client.
Let's have a look at an example Railo Server template:
<html>
<head><title>An Example Template</title></head>
<body>
<div id="AccountHeader">
<cfif SESSION.loggedIn>
<h3>Private bank account No.:
<cfoutput>#bank.accountNr#</cfoutput>
Show secret information
</cfif>
</div>
</body>
</html>
The highlighted code above shows you some CFML (or Railo Template) code. This code is dynamic and will run on the server before returning the rendered HTML back to the browser that requested the page.
If you are used to reading HTML code, you can easily figure out what the previous code is supposed to do. (It displays the HTML between the <cfif> tags if the variable loggedIn in the SESSION is true.)