The document type appears to the far right of each item on the results list page. In this way you can easily identify the kind of records your search returned, such as Article, Biography, Map or Topic Overview, to name a few.
To restrict results to a particular type of document, perform a Basic or Advanced Search. The Search sidebar on the results list page allows you to refine your search. From the Narrow Results by drop-down menu, select "Document Type." The Search sidebar will refresh itself and display all document types that are currently present in the tab displayed, along with the number of results in parentheses. Click the hyperlinked document type and results number to view just those types of documents. Also, when creating an Advanced Search, you may limit your search to certain kinds of document types.