Dark matter is a hypothetical form of matter that does not interact with light or other forms of electromagnetic radiation in the same way that regular matter does. It does not absorb, emit, or reflect light, which is why it is called "dark" matter. It is invisible to our current telescopes and detectors that rely on detecting electromagnetic radiation.
The presence of dark matter is inferred through its gravitational effects on visible matter and the structure of the universe. Astronomers have observed that the visible matter alone cannot account for the observed gravitational effects, indicating the existence of additional matter that interacts primarily through gravity. This is what we refer to as dark matter.
While dark matter does not emit or absorb light or heat as far as we know, it is possible that it could interact through other forces that we have not yet discovered. Various theories have been proposed to explain the nature of dark matter, including some that suggest it might have weak interactions with ordinary matter or itself. However, these interactions, if they exist, would occur on a scale and at energies that are currently beyond our experimental capabilities to detect.
Therefore, the current understanding is that dark matter interacts predominantly through gravity and has negligible interactions with electromagnetic radiation, making it difficult to directly detect or observe using traditional observational methods.