DOM is Document Object Model. The entire XML document is loaded into the memory and is stored in the tree structure. So we can have easy traversal. In the case of large xml documents better to use SAX coz the entire document is loaded into the memory which is memory consuming.

SAX is Simple API for XML parsing it is event driven means for every tag an event is fired like start tag end tag etc. The document is not loaded into the memory as DOM. you have to handle the events (which most programmers try to esacape :)

Thanks and Regards

Eshwar