A tool used for measuring length is called a ruler or a measuring tape. Rulers are typically flat and straight, often made of wood, plastic, or metal, and are used for measuring short distances. Measuring tapes are flexible, allowing for measurements of curved or irregular surfaces. Both instruments are essential in various fields, including construction, tailoring, and crafting. In addition to these, there are also other specialized measuring tools like calipers for precise measurements in engineering or carpentry. Overall, these tools are fundamental for accuracy in both everyday tasks and professional applications.