mostsignificantbitfirst

Most significant bit first, often abbreviated as MSB first or big-endian, refers to a convention for ordering the bits within a multi-bit data unit. In this ordering, the bit with the highest value, or "most significant," is transmitted or stored first. This is analogous to how we write numbers in decimal, where the most significant digit appears on the left. For instance, in an 8-bit byte representing the decimal number 170, the binary representation is 10101010. In MSB first order, this would be transmitted or stored as the sequence 1, 0, 1, 0, 1, 0, 1, 0.

The opposite convention is least significant bit first, also known as LSB first or little-endian, where the bit with the lowest value is transmitted or stored first. The choice between MSB first and LSB first is a design decision made for specific hardware architectures, communication protocols, and data formats. Different systems may use different endianness conventions, which can lead to interoperability issues if not handled correctly. For example, network protocols like TCP/IP typically use MSB first ordering, while many modern microprocessors, such as those in the x86 family, use LSB first. When data is exchanged between systems with different endianness, a process called byte swapping or endianness conversion is necessary to ensure data is interpreted correctly. This ordering convention applies not only to bits but also to bytes within larger data structures like words and double words.