The fundamental forces of nature are the interactions between the particles, which remain unexplained in terms of other kind of forces, or interactions. The most fundamental interactions of nature can be counted as four in number, which can be described as gravitational interactions, electromagnetic interactions, strong and weak nuclear interactions.
Gravitational Forces: It is one of the weakest forces found in the universe and hence, in particle physics, is often neglected. However, macroscopic study of nature shows that there is a large contribution of these forces in most natural phenomenons. It is the only force, which binds the whole universe and millions of galaxies, all together. It is a single-natured force i.e. it has only attractive nature. This force is a mass dependant force i.e. if mass of the particle is more, then the force of gravitation is also high. Moreover, this force is an infinite-ranged force.
Electromagnetic Forces: It is an infinite-ranged force, similar to the gravitational force but a number of times stronger than it are. It is the fundamental force acting between any two electrically charged particles separated by any distance. It is the force, which explains some basic natural events such as friction, lightning and many of the devices such as lasers, televisions, and all electrical components. It, as well, explains the structure of compounds such as chemical bonding theory. Most of the objects in the universe are electrically neutral and hence, this force is not observed much.
Weak Nuclear Forces: The weak interactions are the forces that are responsible for phenomenon such as beta-decay. The weak interaction is the only interaction, which does not conserve parity i.e. it is left right asymmetric. Electromagnetism and weak forces are now considered as a unified force, named as the electro-weak force. This was the first step toward the unified theory, known as the Standard theory. The carriers of the weak force are the massive gauge.
Strong Nuclear Forces: This is probably the most complicated interactions because of the variation of these interactions with distance. At distances greater than 15 femtometers, the presence of this force is not observed. These interactions are very strong and important for small inter-nuclear distances. This force is actually responsible for binding the nucleons viz. neutrons and protons, together inside the nuclei against the electrostatic repulsion between them due to very small particle distances.
Hence, these are the four fundamental forces of nature, which probably rule the every possible event or phenomenon occurring in the whole of universe.
