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>
    <allimages>
      <img name="IMG_5563.jpg" timestamp="2013-03-13T11:54:21Z" user="Scuola Media" url="http://gullp.net/comenius/images/0/08/IMG_5563.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:IMG_5563.jpg" ns="6" title="File:IMG 5563.jpg" />
      <img name="9Molinia_e_prugnoli_selvatici_in_autunno_.jpg" timestamp="2013-03-13T11:46:16Z" user="Scuola Media" url="http://gullp.net/comenius/images/f/f7/9Molinia_e_prugnoli_selvatici_in_autunno_.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:9Molinia_e_prugnoli_selvatici_in_autunno_.jpg" ns="6" title="File:9Molinia e prugnoli selvatici in autunno .jpg" />
      <img name="IMG_5586.jpg" timestamp="2013-03-13T11:41:55Z" user="Scuola Media" url="http://gullp.net/comenius/images/6/6a/IMG_5586.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:IMG_5586.jpg" ns="6" title="File:IMG 5586.jpg" />
      <img name="4._Terza_pista_della_Todt,_con_biancospino_in_fiore.jpg" timestamp="2013-03-13T11:37:33Z" user="Scuola Media" url="http://gullp.net/comenius/images/0/01/4._Terza_pista_della_Todt%2C_con_biancospino_in_fiore.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:4._Terza_pista_della_Todt,_con_biancospino_in_fiore.jpg" ns="6" title="File:4. Terza pista della Todt, con biancospino in fiore.jpg" />
      <img name="7._Bosco_di_robinie.jpg" timestamp="2013-03-13T11:37:29Z" user="Scuola Media" url="http://gullp.net/comenius/images/7/79/7._Bosco_di_robinie.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:7._Bosco_di_robinie.jpg" ns="6" title="File:7. Bosco di robinie.jpg" />
      <img name="2._In_autunno,_affiancata_da_farnie.jpg" timestamp="2013-03-13T11:36:45Z" user="Scuola Media" url="http://gullp.net/comenius/images/8/80/2._In_autunno%2C_affiancata_da_farnie.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:2._In_autunno,_affiancata_da_farnie.jpg" ns="6" title="File:2. In autunno, affiancata da farnie.jpg" />
      <img name="IMG_5630.jpg" timestamp="2013-03-13T11:26:58Z" user="Scuola Media" url="http://gullp.net/comenius/images/e/e9/IMG_5630.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:IMG_5630.jpg" ns="6" title="File:IMG 5630.jpg" />
      <img name="Ginestre.jpeg" timestamp="2013-03-13T11:24:53Z" user="Scuola Media" url="http://gullp.net/comenius/images/e/e8/Ginestre.jpeg" descriptionurl="http://gullp.net/comenius/index.php?title=File:Ginestre.jpeg" ns="6" title="File:Ginestre.jpeg" />
      <img name="11.La_brughiera_in_autunno;_ginestre,_brugo,_pini_silvestri_e_betulle_.jpg" timestamp="2013-03-13T11:08:21Z" user="Scuola Media" url="http://gullp.net/comenius/images/9/9c/11.La_brughiera_in_autunno%3B_ginestre%2C_brugo%2C_pini_silvestri_e_betulle_.jpg" descriptionurl="http://gullp.net/comenius/index.php?title=File:11.La_brughiera_in_autunno;_ginestre,_brugo,_pini_silvestri_e_betulle_.jpg" ns="6" title="File:11.La brughiera in autunno; ginestre, brugo, pini silvestri e betulle .jpg" />
      <img name="Rastilòm.jpeg" timestamp="2013-03-13T11:04:31Z" user="Scuola Media" url="http://gullp.net/comenius/images/9/9b/Rastil%C3%B2m.jpeg" descriptionurl="http://gullp.net/comenius/index.php?title=File:Rastil%C3%B2m.jpeg" ns="6" title="File:Rastilòm.jpeg" />
    </allimages>
  </query>
  <query-continue>
    <allimages aistart="2013-03-13T11:04:30Z" />
  </query-continue>
</api>