The SOAP Header is very much akin to a HTTP header.

SOAP aims to be transport independent (HTTP, SMTP, send())


Sample SOAP Header
<?xml version="1.0"?>
<Envelope xmlns="http://schemas.xmlsoap.org/soap/envelope/">
 <Header>
  <authinfo xmlns="http://www.edwardbear.org/auth/schema/">
   <username>Sterling</username>
   <password>IHonLeiSiebnTognInEuropa</password>
  </authinfo>
 </Header>
 <Body>
 </Body>
</Envelope>