Sometimes we need to measure things. In most cases, when we need to measure something, we use a standard ruler or tape measure. These are normally divided into inches or centimeters depending on the measurement system you are using. To measure something that requires a very fine tolerance you would probably use micrometers. A micrometer allows you to measure things very accurately. Micrometers are often used to measure machine parts to make sure they are within tolerance. Can you think of something that you use every day that might require parts that need exact measurements?