What is a template and a template tag?
A template is a file that is processed by Movable Type to produce a text file suitable for web publishing, such an HTML file (which is most common), a PHP file, a JavaScript file, a CSS file, etc.
Designers utilize template tags within a template to easily parameterize the output of the template itself.
In many respects, Movable Type’s templating language, the collection of all of Movable Type’s template tags, is a programming language unto itself. It is as functional as PHP and JavaScript, but has more in common with HTML as it utilizes a more semantic, tag or markup oriented approach to templating.
Let’s compare Movable Type’s templating language side-by-side with PHP:
PHP
<html>
<head>
<title><?php echo $BLOG_NAME; ?></title>
</head>
<body>...</body>
</html>
Movable Type Template Tag Syntax
<html>
<head>
<title><mt:BlogName></title>
</head>
<body>...</body>
</html>
As you can see they are virtually identical. We will leave the debate of language aesthetics to the uber-geeky.