In computing, the most significant bit (msb) is the bit position in a binary number having the greatest value. The msb is sometimes referred to as the left-most bit, due to the convention in positional notation of writing more significant digits further to the left.

In referencing specific bits within a binary number, each bit is assigned a bit number, ranging from zero to n (depending on the number of bits in the number.) The phrase bit zero may refer to either the least significant bit (lsb) or the msb, depending on the endianness.

By extension, the most significant bits (plural) are the bits of the number closest to, and including, the msb.

MSB, in all capitals, can also stand for "most significant byte". The meaning is parallel to the above: it is the byte in that position of a multi-byte number which has the greatest potential value.

See also

• Least significant bit
• Binary numeral system
• Signed number representations
• Two's complement

Computer arithmetic

Bitwertigkeit | Bit más significativo | Bit de poids fort | 最上位桁ビット | Most significant bit | MSD