Association of numbers with physical quantities and natural phenomena by comparing an unknown quantity with a known quantity of the same kind. Weights and measures are standard quantities with which such comparisons are made. The earliest ones measured mass (weight), volume (liquid or dry measure), length, and area using units mostly based on dimensions of the human body. The cubit, representing the distance from elbow to fingertips, was the most widespread unit of measure in the ancient world. As such units were standardized, more were added, including units of temperature, luminosity, pressure, and electric current. Measurements made by the senses instead of by measurement devices are called estimates (see estimation).

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• Instrument (film)
• Instruments (band), a Canadian recording ensemble
• Instruments (application), a performance visualizerTypes of instruments
• Musical instrument, a device designed to produce music
• Financial instrument, a formal documentation of a financial transaction
• Flight instruments, the devices used to control aircraft
• Instrumental variable, a method used in statistics
• Laboratory equipment, the tools used in a scientific laboratory
• Measuring instrument, a device used to measure or compare physical properties
• Medical instrument, a device used to diagnose or treat disease
• Legal instrument, a formal documentation of a status or transaction
• Negotiable instrument, a type of contract
• Scientific instrument, a device used to collect scientific data
• Statutory instrument, a form of legislation
• Vehicle instrument, a device measuring parameters of a vehicle, such as speed
• Weather instrument, a device used to record aspects of the weather
• A tool used to conduct torture

See also

• Instrumentation (disambiguation)