1. Volume: Gases occupy the entire volume of the container they are in. They expand to fill the available space.

2. Shape: Gases do not have a definite shape. They take the shape of the container they are in.

3. Density: Gases have a relatively low density compared to solids and liquids.

4. Pressure: Gases exert pressure on the walls of the container they are in. The pressure increases as the temperature increases or the volume decreases.

5. Diffusion: Gases can diffuse or spread out on their own, mixing with other gases.

6. Thermal expansion: Gases expand when heated and contract when cooled.

7. Compressibility: Gases are easily compressible, meaning their volume can be reduced by applying pressure.

8. Molecular motion: Gas particles are in constant rapid motion, moving in straight lines until they collide with other particles or the walls of the container.

9. Kinetic energy: The gas particles have kinetic energy, which is the energy of motion. The temperature of a gas is a measure of the average kinetic energy of its particles.

10. Collisions: Gas particles collide with each other and with the walls of the container. These collisions are mostly elastic, meaning the total kinetic energy of the particles is conserved.

Understanding the characteristics of gases is important in various fields such as chemistry, physics, and engineering, and has applications in many areas including gas storage, transportation, heating, and industrial processes.