The hourglass consists of two glass bulbs connected by a narrow neck that allows sand to flow from the top bulb to the bottom one.
The time measured by an hourglass depends on the amount of sand, the size of the bulbs, and the width of the neck.
Sand timers are often used for decorative purposes, as well as for time management in various activities like cooking, exercising, or meditation.
They are also a common symbol for the passage of time and are frequently depicted in art and on monuments