Radiation is used for diagnostic and therapeutic purpose both. Radiation Therapy is being used as primary definitive treatment or as adjuvant treatment for various malignancies. In Radiation Therapy we use the ionizing radiation to kill the tumour cells along with minimal damage to surrounding normal tissue. With the advancement in imaging and treatment modalities and techniques, now we can escalate the radiation dose to the tumour along with better sparing of surrounding normal tissue. In this article we are trying to review the various important aspects of radiation like its evolution and new advancements in radiation techniques.