Editing Help:Template (section)

==Terminology==
A ''template'' is a Wikipedia page whose purpose is to be transcluded or substituted in another page.  Templates are usually in the [[WP:Template namespace|template namespace]], but don't have to be.  Pages can transclude or substitute any page, not just templates; what makes a page a template is the page's purpose.

''Calling'' a template means transcluding or substituting one.  A page calls a template.  The wikitext on a page that causes the page to call a template is called a ''template call''.  For example, <syntaxhighlight lang="wikitext" inline>{{sic|constellation prize}}</syntaxhighlight>.  Template calls are always delimited by double braces (<syntaxhighlight lang="text" inline>{{}}</syntaxhighlight>), but not everything enclosed in double braces is a template call.

''Expansion'' is the process of generating page source from a template, when a page calls it, by applying parameters and other features.  MediaWiki expands a template as it renders a page.  One can also say that the template itself expands, so both "MediaWiki expands {{param|1}} as the value of the first positional parameter" and "{{param|1}} expands as the value of the first positional parameter" work.

''Expansion'' of a page is also the page source that results from template expansion.  For example, the expansion of the {{tl|sic}} template when called by <syntaxhighlight lang="wikitext" inline>{{sic|constellation prize}}</syntaxhighlight> is <syntaxhighlight lang="wikitext" inline>constellation prize&#32;&#91;''[[sic]]''&#93;</syntaxhighlight>.

The displayed page content generated by a template call (which is the rendering of the expansion of the called template) is the ''template result''.  The template result generated by the template call <syntaxhighlight lang="wikitext" inline>{{sic|constellation prize}}</syntaxhighlight> is "{{sic|constellation prize}}".

The ''name'' of a template is the name of the Wikipedia page (which is also the title of the page).  The namespace is normally left off if it is "Template" (which it almost always is).  Furthermore, it is customary to write the name with double braces, like a template call, to emphasize that it names a template.  For example, "Use the {{tl|tm}} template to generate the trademark symbol."  But don't go so far as to put a template name in the code font, to prevent confusion with an actual template call. {{tlf|tm}} is a template name, but {{tnull|tm}} is a template call.

Some template calls perform a tagging function; such a template call is often called a ''tag'', as in, "If you are in the middle of a major edit, place an {{tl|in use}} tag at the top of the page."  This is one of many ways the term "tag" is used in Wikipedia.

A ''parameter'' is a particular piece of information that can be specified in a template call to affect the expansion of the template.  A parameter has a ''value''.  A named parameter has a ''name''; an unnamed parameter has a ''position''.  A template call ''specifies'' a parameter and the code that does that is a ''parameter specification''.  A template ''defines'' a parameter (not explicitly -- just by the template being designed to use it).  The code in a template that expands to the parameter value (e.g. {{param|myparam}}) is a ''parameter reference''.

===Common variations===
It is common to use "template" to refer not only to a template, but to a template call, a template result, and a template name.  

For example: 
* I am going to put more detail in the {{tl|short description}} template on this page.
* Upon seeing an {{tl|under construction}} template, the reader may decide to come back later.
* There are many kinds of infoboxes. The templates all start with "Infobox".

These usages can be confusing, especially to someone less familiar with templates. Consider using more specific language.