Integrated circuit testing connects abstract chip design with physical silicon behavior. A chip may pass extensive functional verification before fabrication, but manufacturing introduces physical imperfections that cannot be eliminated by design verification alone. Defects such as opens, shorts, resistive interconnects, contamination, and process variation can cause the fabricated device to deviate from its intended gate-level implementation. Manufacturing test provides the mechanism for identifying these deviations before defective devices reach customers. The technical foundation begins with the design abstraction flow. Functional intent is refined into RTL, gate-level logic, and physical layout, with verification applied throughout the process to preserve correctness. Once the gate-level design is fixed, the functional behavior is already defined. Manufacturing test does not validate whether the original design is correct; it checks whether the silicon accurately implements that design. This distinction separates design verification from production test and clarifies why passing test means “built as designed,” not necessarily “designed correctly.” Physical manufacturing defec...