Holland codes, also known as Holland Occupational Themes, are a classification system developed by psychologist John L. Holland. They are used to categorize individuals’ interests, personality traits, and work preferences into six broad occupational themes: R, I, A, S, E, C. The Holland codes provide a framework for understanding individuals’ interests and work-related preferences. By identifying their dominant themes, individuals can explore career options that align with their strengths and values and make more informed decisions about their professional paths.