Height-for-weight is an index comparing a child’s height with the average height expected for a child of that weight — used to judge whether growth is proceeding normally and nutrition is adequate. A child who is short for their weight may be stunted from chronic undernutrition; one who is light for their height may be wasted from acute hunger. Anthropometrists prefer standardised z-scores against WHO growth references today, but the underlying principle is the same: growth is the most sensitive single indicator of a child’s nutritional status, and deviations flag problems long before clinical deficiency appears. Field workers with tapes and scales can thus screen whole populations for malnutrition.