Heijunka
tool is used for scheduling production in a pull system. The overall leveling, in the production schedule, of the volume and variety of items produced in given time periods. Heijunka is a pre-requisite for just-in-time delivery.

Histogram
a graphical representation of a frequency distribution in the form of rectangles whose bases are equal to the cell interval and whose areas are proportional to the frequencies. Click here for a sample.

Hooke's Law
stress is proportional to strain. This law is valid only up to the proportional limit, or the end of the straight-line portion of the stress-strain curve.

Homeostasis
the stability of a system's internal environment, despite having to cope with an unpredictable external environment.