Radar systems are increasingly critical in various applications, from automotive safety to air traffic control and military operations. However, radar interference remains a significant challenge, impacting the reliability and accuracy of radar systems. This review paper provides a comprehensive examination of radar interference mitigation techniques, emphasizing their practical applications, advantages, and limitations. Specific examples such as automotive radar experiencing mutual interference in dense traffic or weather radars facing clutter from wind turbines are discussed. We explore classical approaches such as filtering and time-domain gating, alongside advanced methods leveraging machine learning and adaptive signal processing. The discussion synthesizes current research trends and identifies gaps, offering insights for future development in the field.