Here is a very simple template:
This template is called hello. The name appears first in bold. After that come zero or more parameters in parentheses. Most of the templates you define will, like this one, have no parameters.Hello () TEXT "Hello world!"
After the name and the parameters come one or more RTML expressions. In this case there is just one, a TEXT expression. The TEXT operator takes one argument and prints it on the current page.
The argument in this case is the string "Hello world!", so that (without the quotes) is exactly what will appear on the page being generated.
Since this template doesn't refer to any of the properties of the current object, it will generate the same page no matter which object it is being used to display.
Such a template might actually be useful in some situations. For example, you might define a template that simply printed "Under construction" and use that as the template of any objects in your site that you didn't want people to see yet.