Lets say word size is 4 bytes and the corresponding bytes be W, X, Y and Z. Now if the word is to be stored at address 0-3, we have two options:
- W X Y Z - lowest address taken by highest order byte
- Z Y X W - lowest address taken by lowest order byte
First one is big-endian (most significant byte first) and second one is little-endian (least significant byte first).