Secondary education is the formal schooling stage following primary education and preceding higher education, typically serving adolescents aged approximately 11 to 18. As an academic concept and research field, it investigates the structure, curriculum, pedagogy, and outcomes of this educational level, focusing on students' cognitive, socio-emotional, and academic development and their preparation for diverse post-compulsory pathways including higher education and the workforce. Its significance lies in its crucial role as a transitional phase that shapes individuals' foundational knowledge, skills, and future opportunities within educational systems globally.