RSS 1.0 and 2.0 Anatomy

RSS 1.0/2.0 files start with the XML version declaration:

<?xml version="1.0"?>

RSS 1.0 continues with a dtd, and channel meta info:

<rdf:RDF [dtd/namespace information]>
 <channel rdf:about="someurl">
  [some channel tags with meta info]
 </channel>
 <image>
  [channel image info]
 </image>

RSS 2.0 declares the RSS version, and begins the <channel> tag:

<rss version="2.0"
 <channel>
  [some channel tags with meta info]

Each RSS 1.0/2.0 feed can have multiple news items enclosed within <item> and </item>.

Remember this part:

This presentation parses three <item> subtags common to RSS 1.0 and 2.0:

  <item>
   <title>
    [Title Text]
   </title>
   <link>
    [source URL]
   </link>
   <description>
    [descriptive summary]
   </description>

After the last <item>, RSS 1.0 closes with:

 <textinput>
  [more channel info]
 </textinput>
</rdf:RDF>

RSS 2.0 closes with:

 </channel>
</rss>

Reference: Wikipedia - RSS (file format)