In Big-Endian system A)MSB of data in the lowest memory address of data unit. i.e. if we write an integer of 4 bytes say 127 = 0x0000007f, it will be written to memory as 00 00 00 7f, where each consecutive 2 characters represent a byte. In little-endian, the memory content would be 7f 00 00 00. (Now you should know how to identify if a system is little-endian or big-endian).