A conference that is usually intended to achieve organizational and clarification objectives, such as resolving certain legal issues, stipulating facts, amending pleadings, and identifying witnesses and exhibits for the trial.
A pretrial conference is a meeting, usually in a courthouse setting, in which the parties and their attorneys meet for the purpose of trying to obtain a settlement. The conference is normally moderated by a judge or referee who is handling the matter. If the case cannot be settled and the matter gets set for trial, a pretrial order is issued.
Any time both sides of the case go to court before trial. In criminal cases, it's usually when the defendant and prosecutor talk about settling the case.