Boundary Scan cells are specialized components used in integrated circuits to facilitate testing and debugging. They are part of the IEEE 1149.1 standard, commonly known as JTAG (Joint Test Action Group). These cells are placed at the boundaries of a chip, allowing external test equipment to access and control the internal circuitry without needing physical probes. When a chip is tested, the Boundary Scan cells can shift data in and out, enabling the detection of faults and ensuring proper functionality. This method enhances the testing process by simplifying connections and reducing the need for complex test fixtures, making it easier to identify issues in printed circuit boards and integrated circuits.