Game modifier (lazer)
Note: For the osu!(stable) version of this article, see Game modifier
Note: For other uses of "mod", see Mod (disambiguation)
/img/mod-select.jpg "Mod selection screen for the osu! game mode")
Mod selection screen for the osu! game mode
Game modifiers, or mods, are separated into six categories: Difficulty Reduction, Difficulty Increase, Automation, Conversion, Fun and System. They can have various effects on gameplay, such as visual adjustments to a beatmap's hit objects or the speed at which the map is played. Mods from the System category are applied automatically when necessary.
Mod multiplier
Main page: Mod multiplier (lazer)
Some mods can reduce or increase the score multiplier. When multiple mods are used simultaneously, their respective multipliers will usually be multiplied together (e.g. 1.04x * 1.09x = 1.1336x). There are some exceptions to this, which are pointed out in the articles of the affected mods.
List of mods
Next to each of the mods listed below the icons of their compatible 
game modes are displayed.
Difficulty Reduction
Difficulty Increase
Automation
Conversion
Fun
System
Personal Presets
The Personal Presets are located in a separate category (left of Difficulty Reduction) and allow players to save any combination of mods directly into it. Each personal preset has to be assigned a name and optionally a description. Every game mode has a separate list of personal presets.