The version history of items such as pages, images, news, etc provides a list of all the edits/changes made to such items. Each time changes are made to an item, a new version is saved. These various versions will then be listed under "History".
Working Copy allows you to work on a parallel copy of a page so that edits can be made at leisure while the original version is still live to site visitors.
Portlets are dynamically generated or static content views that can be displayed in special parts of the site layout. There are two basic kinds: fixed-column portlets and content well portlets.
Need another calendar? One specifically for students? Or a web-based Intranet calendar for your department? Add one by changing the settings of a folder.