Overmapping
In beatmapping, overmapping is a technique where hit objects are deliberately placed in a way that creates a higher gameplay intensity compared to what the song (or the rest of the map) conceivably calls for.
This is mainly done by mapping to inaudible or non-existant sounds (e.g. adding notes on blue ticks when the song has sounds only on red ticks). Less frequently, overmapping can also be achieved by adding exorbitantly large jumps or sliders with very high slider velocity.
Examples
Example of overmapping by excessively high object density
Example of overmapping by excessively high object spacing
Example of overmapping by excessively high slider velocity
While overmapping by itself is generally discouraged, there are contexts where the technique is acceptable, such as when the added rhythm fits the song and creates emphasis that benefits the map's quality.