When a user hovers the mousepointer over a wiki link, a small preview window is shown. The preview window will show the page's first image (if any) and the first paragraph or so.

Install the plugin using the Extension Manager and the download URL above, which points to latest version of the plugin. Refer to Plugins on how to install plugins manually.

A CSS selector can be configured in the settings. All .wikilink1 links within that selector will have the preview mechanims attached.