ruler
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AI overview
A ruler is a straightedge tool marked with measurements (like inches or centimeters) that people use to draw straight lines and measure distances. It matters because it's a simple but essential tool for many everyday tasks in drawing, writing, construction, and crafting.
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Article
8 sectionsContents
- Variants
- Use in geometry
- History
- Curved and flexible rulers
- Philosophy
- See also
- References
- Bibliography
thumb|right|upright=1.3|A variety of rulers thumb|right|A carpenter's rule thumb|right|Retractable flexible rule or tape measure thumb|right|A closeup of a steel ruler thumb|A ruler in combination with a letter scale
A ruler is an instrument used to make length measurements, whereby a length is read from a series of markings called "rules" along an edge of the device. Alternatively, it is called a rule, scale, line gauge, or metre/meter stick. Usually, the instrument is rigid and the edge itself is a straightedge ("ruled straightedge"), which additionally allows one to draw straighter lines. Rulers are an important tool in geometry, geography and mathematics. They have been used since at least 2650 BC.