Emotional Intelligence (EI) has become a critical concept in understanding human behavior and performance across various domains. Initially defined by Salovey and Mayer in 1990, EI encompasses the ability to perceive, understand, regulate, and use emotions to guide thinking and actions. As research on EI has expanded, it is now recognized as a key factor in enhancing communication, leadership, collaboration, and resilience in fields such as education, healthcare, psychology, and business. This paper examines the conceptual evolution of EI and reviews major theoretical frameworks: the skills model, which views EI as learnable cognitive abilities; the personality model, which sees EI as a stable trait; and the mixed model, which integrates emotional competencies with personality attributes. These models provide diverse methods for assessing and applying EI in real-world settings. Importantly, EI is increasingly seen as distinct from IQ, offering valuable insights into emotional regulation, interpersonal dynamics, and personal effectiveness. This study highlights the multidimensional nature of EI and underscores its growing relevance in both academic and professional environments.