Endianness (Byte Order)
With the Byte Order (Endianness), the memory organization is designated in computer technology. Every time if more bits than in the smallest addressable unit are required to store something, it is needed to declare in which order the data is stored.
In general, the smallest addressable unit is composed of eight bits, that is one byte. If you have to store more than one byte, there are two possibilities for storage:
One possibility is to start at the large end. Similar to the representation of the time with "hour - minute - second", here, the byte with the most significant bit is stored first, that means, it is stored in the lowest memory address.
The other option is to start at the small end. Like writing the date in the order "day - month - year", here, the byte with the least significant bit is the first one. This byte is then written to the lowest memory address in this case.
Since for the encoding of Unicode text sometimes multiple bytes per character must be written, there is the question of the order of these bytes. Both, Big Endian and Little Endian is allowed in unicode, so there are formats like UTF-16 Big Endian, UTF-16 Little Endian, UTF-32 Big Endian and UTF-32 Little Endian.