When reading chess books or engine analysis, you'll see symbols like !, ?, !!, and ?? after moves. These annotation symbols evaluate move quality. Here is what every symbol means.
Move quality symbols
Symbol
Meaning
Example
!
Good move
A strong move that improves the position
!!
Brilliant move
A surprising, exceptional move (often a sacrifice)
?
Mistake
A move that worsens the position significantly
??
Blunder
A terrible move that loses material or the game
!?
Interesting move
An ambitious move, possibly risky but creative
?!
Dubious move
A questionable move that may not be objectively best