Intelligence Quotient (IQ) tests are standardized psychometric instruments constructed to assess a broad spectrum of cognitive operations under controlled conditions, thereby yielding a quantifiable estimate of an individual’s intellectual functioning relative to a norm-referenced population. As theory and methodology have advanced, IQ is no longer conceptualized as a single, undifferentiated capacity but as an emergent composite of distinct yet interrelated abilities, including verbal reasoning, abstract and fluid problem solving, working memory, and processing efficiency. Historically, the origins of IQ testing can be traced to early 20th‑century educational reforms, where the primary objective was the identification of children requiring tailored instructional support; over time, these early scales have evolved into highly sophisticated, psychometrically robust instruments that are now integral to clinical, educational, and research practice. Contemporary intelligence batteries such as the Wechsler scales and the Stanford‑Binet employ multiple subtests and carefully calibrated scoring procedures, allowing for both a global index of general intellectual ability and a differentiated profile of cognitive strengths and weaknesses. Within this framework, IQ scores are derived through rigorous standardization procedures, in which an individual’s raw performance is statistically transformed and compared against large, demographically stratified normative samples, typically producing a mean of 100 and a standard deviation of 15. Such norm‑referenced interpretation enables practitioners to situate an individual’s performance along the full continuum of intellectual functioning, from significantly below average to exceptionally high, and to do so with known reliability and validity parameters supported by extensive empirical research. Beyond their descriptive utility, IQ tests serve as critical tools in high‑stakes decision‑making contexts, including the diagnosis of intellectual developmental disorders, the assessment of giftedness, neuropsychological evaluation following brain injury, and the design of individualized educational programs. When interpreted within a comprehensive assessment framework that also considers socio‑cultural, emotional, and contextual factors, IQ test results contribute to a nuanced and evidence‑based understanding of human cognitive diversity rather than a reductive, single‑number label.