The hourglass is a device used to measure time, consisting of two glass bulbs connected by a narrow neck. Sand or liquid flows from the upper bulb to the lower one, marking the passage of time. The duration of the measurement depends on the size of the bulbs and the amount of material used. Historically, hourglasses were popular in various cultures, including Ancient Egypt and Medieval Europe. They served practical purposes in activities like cooking and navigation. Today, hourglasses are often used as decorative items or in games, symbolizing the concept of time passing.