Long, narrow tables are positioned in front of rows of chairs facing the speaker. The tables usually abut one another, although tables that extend beyond the stage ideally should be angled toward the speaker in order to provide better viewing. Water pitchers and glasses are typically placed on the tables.
Best setup for situations in which the presenter is expected to do most of the talking and/or delegates must take notes, refer to material in binders, or work on computer equipment. It's also the most comfortable design for very long sessions. It is not the preferred setup for encouraging conversation among attendees.