diff --git a/content/variables/site.md b/content/variables/site.md
index 00b1d20e7..f0c041ecb 100644
--- a/content/variables/site.md
+++ b/content/variables/site.md
@@ -52,6 +52,9 @@ The following is a list of site-level (aka "global") variables. Many of these va
 .Site.IsMultiLingual
 : whether there are more than one language in this site. See [Multilingual](/content-management/multilingual/) for more information.
 
+.Site.IsServer
+: a boolean to indicate if the site is being served with Hugo's built-in server. See [`hugo server`](/commands/hugo_server/) for more information.
+
 .Site.Language.Lang
 : the language code of the current locale (e.g., `en`).
 
@@ -122,4 +125,4 @@ You can use `.Site.Params` in a [partial template](/templates/partials/) to call
 <meta name="description" content="{{if .IsHome}}{{ $.Site.Params.description }}{{else}}{{.Description}}{{end}}" />
 {{< /code >}}
 
-[config]: /getting-started/configuration/
\ No newline at end of file
+[config]: /getting-started/configuration/