A plainlink is a link external to en.wikipedia.org, but in this case not followed by an external link icon. It is used for links internal to en.wikipedia.org which require special URL parameters and therefore cannot be reached by wikilinks.

Making a plainlink

The arrow icon can be suppressed by:

For example,

<span class="plainlinks">[https://en.wikipedia.org/wiki Wikipedia, the free encyclopedia]</span>
((Plain link|https://en.wikipedia.org/wiki|Wikipedia, the free encyclopedia))

produce Wikipedia, the free encyclopedia.

Some templates such as ((Querylink)) and ((Oldid)) use plainlinks.