Links (<a> & <area>) are scanned and some are enriched with mouse-over pop-ups:

Wiki preview

Any link with url: [/...][/by_...]/<wiki-id> will have a pop-up showing the summary/preview of the targeted wiki page (if available)

To have a usable summary/preview view a wiki must have a <summary> tag; any image with a preview_image css class will also be included

e.g. Viralzone Human viruses page

Protein preview

Any link with a title attribute (final parenthesis in wiki markup e.g. "link-text(P98073)":...) without a space, will have a popup showing a preview of the targeted protein (via fetching the protein data from uniprot) if is a valid protein AC & uniprot data is available.

n.b. legacy title in the form "<identifier like embl>:<tax-id>" that were supposed to use StringDb summaries do not work anymore

e.g. Viralzone Host G2/M cell cycle arrest by virus

Internal pop-ups

Any link with a lang attribute in the form +<existing-html-element id>, will have a popup showing the existing-html-element content

e.g. Viralzone COVID-19 vaccines

Wikipedia preview

Any link to wikipedia will have the wikipedia entry preview popup (is the connection is allowed by web server) ...