What kind of interactions are described by the Standard Model?
The Standard Model describes electromagnetic, weak, and strong nuclear interactions. It does not describe the fourth known fundamental force in nature, gravity.
The Weak Nuclear Force is also described as part of the electromagnetic force. This combined force is now called the Electro-weak Force.
Some scientists have proposed that the Strong Nuclear Force may be able to be combined with the other forces. So far, no models have been shown to be successful in unifying these forces.
Gravity, the weakest of the fundamental forces, is also the force which we know the least about. Detectors have been built to explore gravity waves, but none have yet been detected.
String Theories and other Grand Unification Theories propose systems which can describe all of the forces together. So far, these theories have not produced any testable claims. Many even predict that the only tests for quantum string interactions would require more energy than our entire planet is capable of producing. So, for now, that effort remains theoretical.