A molecular cloud is a dense region in space filled with gas and dust, primarily composed of hydrogen molecules. These clouds are often the birthplace of stars and planets, as their high density allows gravity to pull material together, leading to the formation of new celestial bodies. Molecular clouds can be found in various parts of the universe, including our own Milky Way galaxy. They are typically cold, with temperatures around 10 to 20 Kelvin, which helps preserve the molecules within them. Observations of these clouds are crucial for understanding the processes of star formation and the evolution of galaxies.