Diffuse clouds are a type of interstellar cloud that is less dense than other types, such as molecular clouds. They are primarily composed of gas and dust, and they play a crucial role in the formation of stars and planetary systems. These clouds can be found throughout the galaxy, often serving as the building blocks for more complex structures. The composition of diffuse clouds includes hydrogen, helium, and trace amounts of heavier elements. Their low density allows for the passage of light, making them visible in certain wavelengths. Observations of diffuse clouds help astronomers understand the processes of star formation and the evolution of galaxies.