Fundamental Interactions

All the ways that the simplest particles in the universe interact with one another:

Fundamental Interactions (also called Fundamental Forces)
Note 1: An interaction is fundamental if it cannot be described in terms of other interactions.
Note 2: There are four known fundamental interactions/forces in the universe:
1) Electromagnetism
2) Gravitation
3) Strong Interaction (also known as Strong Nuclear Force)
4) Weak Interaction (also known as Weak Nuclear Force)