In physics, fundamental forces, also known as fundamental interactions, are the basis for explaining essentially all interactions in the universe on a particle level.
Although investigations of fundamental interactions are often the domain of particle physics these interactions, especially electromagnetism and gravity, are the basis of explanations for all most all phenomena we regularly observe.
These forces or interactions provide measurable models for simple interactions from atoms, sub atomic particles to large scale structures like planets, planetary systems.
There are 4 main forces:
There may be other forces that are important to explain certain phenomena such as in cosmology to explain ‘inflation’ of the universe. But these other forces are unique occurrences or do not affect current local interactions in a routine observable way.
Dark matter as a force is speculated to be the result of weakly interacting subatomic particles of some kind.