Endianness

Big-endian systems store the most significant byte of a word in the smallest address and the least significant byte is stored in the largest address. Little-endian systems, in contrast, store the least significant byte in the smallest address.[1]

For example, there is a number in hexadecimal: 0x01234567, with the most significant byte 0x01 and least significant byte 0x67. It is stored within the address range 0x100 through 0x103.[2]

Big-endian:

Address	0x100	0x101	0x102	0x103
Value	0x01	0x23	0x45	0x67

Little-endian:

Address	0x100	0x101	0x102	0x103
Value	0x67	0x45	0x23	0x01

Different processors may follow different conventions. For example the Intel x86 and x86-64 series of processors use the little-endian format while the Motorola 6800 and 68k series of processors use the big-endian format. And newer versions of ARM processors support bi-endian.[1] The most important thing is the consistency. One should keep the used convention in mind when (1) binary data are communicated over a network between different machines; (2) looking at the byte sequences representing integer data, say inspecting machine-level code generated by a disassembler; (3) programs are written that circumvent the normal type system, say using a data type cast in C.