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>
    <allpages apcontinue="Centos_Oneliners" />
  </query-continue>
  <query>
    <allpages>
      <p pageid="249" ns="0" title="Bash Script to Check Memory with Email Alert when Low" />
      <p pageid="250" ns="0" title="Bash Script to Check Site Code Status with Email Alert" />
      <p pageid="185" ns="0" title="Basic HTTP Authentication with Nginx" />
      <p pageid="188" ns="0" title="Basic Redis commands - Cheat Sheet" />
      <p pageid="137" ns="0" title="Batch jpeg Image Optimization" />
      <p pageid="148" ns="0" title="Benchmarking and Load Testing with Apache Bench(AB)" />
      <p pageid="147" ns="0" title="Benchmarking and Load Testing with Siege" />
      <p pageid="97" ns="0" title="Block Bots by User Agent String" />
      <p pageid="24" ns="0" title="Brian Notes" />
      <p pageid="80" ns="0" title="Centos 6" />
    </allpages>
  </query>
</api>