For a number which requires more than a single byte to represent, one must decide in which order to store the multiple bytes;
Big Endian stores the Most significant ("big") byte first (at the lowest address);
Little Endian stores the Least significant ("little") byte first (at the lowest address)

http://www.xerez.demon.co.uk/jargon/B/...ndian.html

http://www.xerez.demon.co.uk/jargon/L/...ndian.html