The symbol , pronounced "little-O of ," is one of the Landau symbols and is used to symbolically express the asymptotic behavior of a given function.
In particular, if is an integer variable which tends to infinity and is a continuous variable tending to some limit, if and are positive functions, and if and are arbitrary functions, then it is said that provided that . Thus, or grows much faster than or .
Note that little-O notation is the inverse of little-omega notation, i.e., that
Additionally, little-O notation is related to big-O notation in that is stronger than and implies .