The back row of pieces is shuffled, (the pawns stay in the front row) this throws out opening theory, and some people really enjoy the aspect of "exploring" every single new game.
Chess 960

Chess960, or Fischer Random Chess, is a chess variant invented by former World Champion Bobby Fischer, originally announced on June 19, 1996, in Buenos Aires, Argentina. It uses the same board and pieces as standard chess, but the starting position of the main pieces is determined randomly. The random setup makes creativity and talent more important than memorization of opening moves.
Randomizing the main pieces has long been known as Shuffle Chess, but Chess960 introduces new rules so that full castling privileges exist in all starting positions, resulting in 960 possible (non-mirrored) positions. To maintain the character of standard chess, the king must start somewhere between the two rooks, and the bishops must start on opposite-color squares.
Starting position requirements
The starting position for Chess960 must meet certain rules. White pawns are placed on the second rank as in regular chess. All remaining white pieces are placed randomly on the first rank, with the following restrictions:
These are pretty much the basics of 960.
I am new here, what is Chess 960 please? I cannot find the definition and/or rules.
Yessss, Duhhh but sorry! I really do not know :-)