**Explanation:**

Liquids are one of the three states of matter, along with solids and gases. Unlike solids, where particles are tightly packed in a rigid pattern, and gases, where particles are far apart and move freely, liquids have a unique property that allows them to flow. This is due to the following characteristics of liquid particles:

**1. Particles in liquids are not tightly packed:**
Unlike solids, where particles are tightly packed together, liquid particles are not tightly packed. They have more space between them, allowing them to move more freely. This lack of tight packing enables liquids to flow.

**2. Particles in liquids can slide past each other:**
In a liquid, the particles are not held in a rigid pattern like in solids. Instead, they are free to move and slide past one another. This sliding motion allows the liquid to change its shape and flow from one place to another.

**3. Liquids have the ability to take the shape of their container:**
Another characteristic of liquids is their ability to take the shape of their container. When you pour a liquid into a container, it fills the container and takes its shape. This is possible because the particles in the liquid can move and slide to fit the shape of the container.

**4. Liquids have a definite volume:**
While liquids can change their shape to fit the container, they still have a definite volume. This means that the amount of liquid remains constant, even if its shape changes. The particles in a liquid are still close enough to each other to maintain their volume.

In conclusion, liquid particles are not tightly packed and can slide past each other. This allows liquids to flow and take the shape of their container. These unique characteristics of liquid particles are what make liquids flow.