The bit error rate (BER) is a measure used to quantify the number of errors in a digital communication system. It is defined as the ratio of the number of erroneous bits to the total number of bits transmitted. A lower BER indicates a more reliable communication system, while a higher BER suggests that the system is experiencing more errors, which can affect data integrity. BER is crucial in evaluating the performance of various technologies, including wireless networks, fiber optics, and satellite communications. Engineers use this metric to design and optimize systems, ensuring that data is transmitted accurately and efficiently, which is essential for applications like streaming video and online gaming.