MSB stands for Most Significant Bit, while LSB stands for Least Significant Bit. In a digital data bit string, the MSB is a bit of the highest digit, and the LSB is a bit of the lowest digit. MSB stands for most significant bit, while LSB is least significant bit. Understanding the most and least significant bit. The most significant bit (MSB) is the bit in a multiple-bit binary number with. MSB stands for Most Significant Bit.