Advanced planning and scheduling (APS) refers to a class of software tools that generate production schedules by respecting real manufacturing constraints. Unlike the infinite capacity planning built into most ERP systems — which assigns work without checking whether machines are actually available — APS introduces finite capacity scheduling. It accounts for machine hours, shift calendars, routing sequences, and setup times to produce schedules that are feasible against actual capacity. Most APS systems use operations research methods at their core: constraint programming, linear programming, mixed-integer programming (MIP), or rule-based heuristics. For manufacturers with stable, predictable environments, APS delivers reliable value and is a significant step forward from spreadsheet-based planning.