As long as you are using rules to measure everyday objects that are on of an appropriate size, you will be able to get a reliable and accurate measurement. The major advantages of rules are that they are pretty cheap in cost and very easy to find. They also come in almost infinite sizes, are made of different materials, and come with different measuring units that can all be specified to the measurement you are taking. A well-made rule can also double as a straight edge for determining flaws or errors in other parts or tools. A major disadvantage of a rule is that it is not a good tool for measuring larger objects or distances that are greater than about a yard or meter. As measurement length becomes greater, the reliability decreases. Similarly, rules can only get down to a gradation of about 1.5mm or 1/16th of an inch. This limits the degree of precision you can accomplish on a smaller scale. Finally, a major consideration when conducting a measurement using a rule is to consider the impact of the observer. Most rules are read by the user and therefore very susceptible to reading error or sight misjudgment. For lower impact, day-to-day jobs, rules are an incredibly handy tool to have around. For higher-impact, very precise measurements you may want to consider using a more intricate measurement device.