Not to be confused with Beatmaps.
A beatmap's difficulty describes the level of skill needed to complete it. The difficulty name and star rating of a beatmap usually give enough information to tell how difficult it is.
See also: Difficulty Naming
These are the typical levels of difficulty that a beatmap can fall under. Specific definitions and requirements of each can be found in their respective mode's ranking criteria.
On the website, beatmaps are automatically given a difficulty icon based on these star rating ranges:
Most maps' intended difficulty levels match the icons they are given, but some deviate significantly. This is why the ranking criteria defines more precise rules for determining difficulty and evaluating beatmapset spreads.