Resonance phenomena is a concept in physics describing the significantly enhanced interaction or reaction rate between particles or systems occurring at specific characteristic energies. This enhancement arises when the energy of the incident particle matches an energy level corresponding to the formation of a transient, unstable excited state of the interacting system. As a research area, it investigates these resonance energies, the properties of the transient states (resonances), and their critical impact on reaction cross-sections, providing fundamental insights into energy-dependent interaction dynamics essential for understanding nuclear reactions in astrophysical environments and engineered systems like nuclear reactors.