This document discusses casting patterns. It begins by defining foundry or casting processes and the basic steps, which include pattern forming, core forming, mould preparation, pouring molten metal, cooling and solidification, and cleaning. Patterns are replicas of the part to be cast and prepare the mould cavity. Common pattern materials include wood, metal, and plastic. Pattern types include single piece, split, loose piece, match-plate, sweep, and gated patterns. Patterns include allowances for shrinkage, draft, machining, distortion, and rapping. Patterns are color coded to indicate surfaces and features like core prints and parting lines.