According to Alledia's Understanding Joomla ItemID, there are two identifiers that are key to calling Joomla content - the ItemID and the ID. What these correspond to are alluded to in Alledia's article.
Key questions are:
- Where to get the Id from
- Where to get the ItemId from
The ItemId is the unique identifier that Joomla! uses to construct your page with the different modules, their positions, and other such page-structure related decisions the CMS has to make.
In addition the option=com_content request parameter is needed to be passed in.