You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <allimages aicontinue="Coffee_nerd.jpg" />
  </query-continue>
  <query>
    <allimages>
      <img name="Ballbathphoto.jpg" timestamp="2015-12-12T00:35:21Z" url="https://events.ccc.de/congress/2015/wiki/images/6/6c/Ballbathphoto.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Ballbathphoto.jpg" ns="6" title="File:Ballbathphoto.jpg" />
      <img name="Bixels.jpg" timestamp="2015-12-10T12:11:16Z" url="https://events.ccc.de/congress/2015/wiki/images/f/f0/Bixels.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Bixels.jpg" ns="6" title="File:Bixels.jpg" />
      <img name="CCCFr_congresseverywhere.png" timestamp="2015-12-21T22:22:18Z" url="https://events.ccc.de/congress/2015/wiki/images/6/66/CCCFr_congresseverywhere.png" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:CCCFr_congresseverywhere.png" ns="6" title="File:CCCFr congresseverywhere.png" />
      <img name="CCH_Entrance_level_with_HHA.jpg" timestamp="2015-12-21T20:54:09Z" url="https://events.ccc.de/congress/2015/wiki/images/4/4b/CCH_Entrance_level_with_HHA.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:CCH_Entrance_level_with_HHA.jpg" ns="6" title="File:CCH Entrance level with HHA.jpg" />
      <img name="Ccc-ch.png" timestamp="2015-11-10T07:55:09Z" url="https://events.ccc.de/congress/2015/wiki/images/a/a1/Ccc-ch.png" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Ccc-ch.png" ns="6" title="File:Ccc-ch.png" />
      <img name="Ccc-ffm-logo-pcb-l.png" timestamp="2015-11-09T23:04:43Z" url="https://events.ccc.de/congress/2015/wiki/images/1/16/Ccc-ffm-logo-pcb-l.png" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Ccc-ffm-logo-pcb-l.png" ns="6" title="File:Ccc-ffm-logo-pcb-l.png" />
      <img name="Ccc_pdf_fuzzinozer.pdf" timestamp="2015-12-27T06:54:46Z" url="https://events.ccc.de/congress/2015/wiki/images/8/8d/Ccc_pdf_fuzzinozer.pdf" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Ccc_pdf_fuzzinozer.pdf" ns="6" title="File:Ccc pdf fuzzinozer.pdf" />
      <img name="Cch_to_fhb_centro_path_map.jpg" timestamp="2015-12-27T07:03:19Z" url="https://events.ccc.de/congress/2015/wiki/images/c/ca/Cch_to_fhb_centro_path_map.jpg" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Cch_to_fhb_centro_path_map.jpg" ns="6" title="File:Cch to fhb centro path map.jpg" />
      <img name="Chaos-macht-Schule-Logo-final.png" timestamp="2015-11-29T23:19:04Z" url="https://events.ccc.de/congress/2015/wiki/images/0/00/Chaos-macht-Schule-Logo-final.png" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Chaos-macht-Schule-Logo-final.png" ns="6" title="File:Chaos-macht-Schule-Logo-final.png" />
      <img name="Chaoswelle_320.png" timestamp="2015-12-23T20:11:29Z" url="https://events.ccc.de/congress/2015/wiki/images/b/b9/Chaoswelle_320.png" descriptionurl="https://events.ccc.de/congress/2015/wiki/File:Chaoswelle_320.png" ns="6" title="File:Chaoswelle 320.png" />
    </allimages>
  </query>
</api>