In descriptive statistics, the five-number summary of a data set consists of:

1. the minimum (smallest observation)
2. the lower quartile or first quartile (which cuts off the lowest 25% of the data)
3. the median (middle value)
4. the upper quartile or third quartile (which cuts off the highest 25% of the data)
5. the maximum (largest observation)

See also: Quartile, Median, Order statistic, Box plot