Boundary Scan Testing is a method used to test the interconnections between integrated circuits on a printed circuit board (PCB). It utilizes a special test access port and a set of standardized protocols, allowing engineers to check for faults without needing physical access to the pins of the chips. This technique is particularly useful for complex boards where traditional testing methods may be difficult or impossible. The process involves adding Boundary Scan cells to the chips, which can shift in test data and capture output data. By using a test program, engineers can identify issues such as shorts or opens in the connections, ensuring the reliability and functionality of the electronic device.