In this handout, we'll explore the mysterious cosmic environment known as the interstellar medium (ISM). The ISM is a fascinating tapestry of gas, dust, magnetic fields, and cosmic rays that fills the space between celestial bodies, shaping the evolution of galaxies and giving birth to new stars and planetary systems.

Galaxies are extremely important large scale-structures in the Universe, containing millions of stars and planets. In this handout we will delve into the vast expanse of galaxies and explore the diverse array of shapes, structures, and properties they exhibit. Moreover, we will explore the intriguing phenomenon of Active Galactic Nuclei (AGN), where supermassive black holes at the centers of galaxies unleash extraordinary amounts of energy.