Scheduled conferences can exist as either current conferences or archived conferences. Typically, scheduled conferences that have outstanding timelines (papers are still being accepted; registrations are still being taken; the conference itself is in progress) are considered 'current' conferences, although it is possible to override some settings and archive a conference prematurely.
The Conference Manager can set when a scheduled conference is archived from the Conference Timeline page located on the Conference Site Management page.
Current and archived conferences are available from their respective top navigation bar links when viewing a hosted conference.