What does this template snipped do? [solved]

I saw this little template snippet and asked myself, what the .isNode part actual does?

<meta name="description" content="{{ if .IsNode }}{{ with .Site.Params.description }}{{ . }}{{ end }}{{ else }}{{ with .Description }}{{ . }}{{ end }}{{ end }}">

That snippet adds a pre-defined description (from the site general config file) for the pages that don’t have a content file. Content files can have a description front-matter field.

Node definition via the docs:

In Hugo, a node is any page not rendered directly by a content file. This includes taxonomies, lists and the homepage.

And .IsNode is currently the same as not .IsPage

Thanks for the replies @dplesca and @bep.