Water displacement is a method used to measure the volume of an irregular object. It works on the principle that when an object is submerged in water, it displaces an equal volume of water. By measuring the volume of the displaced water, we can determine the volume of the object.

Here are some reasons why water displacement is used:

1. Accuracy: Water displacement is a very accurate method of measuring volume. It is more accurate than methods like using a ruler or measuring tape, which can be affected by the shape and irregularities of the object.

2. Simplicity: Water displacement is a simple and straightforward method that does not require any specialized equipment. All you need is a container of water, a graduated cylinder, and the object whose volume you want to measure.

3. Non-destructive: Water displacement is a non-destructive method, meaning that it does not damage or alter the object being measured. This makes it suitable for measuring the volume of delicate or fragile objects.

4. Versatility: Water displacement can be used to measure the volume of a wide variety of objects, regardless of their shape or size. This makes it a versatile method that can be used in various applications.

5. Educational value: Water displacement is a valuable teaching tool that can be used to demonstrate the concept of volume and density to students. By conducting water displacement experiments, students can gain a deeper understanding of these concepts and how they apply to real-world objects.

Overall, water displacement is a widely used method for measuring volume due to its accuracy, simplicity, non-destructive nature, versatility, and educational value.