The moduli theory of line bundles is arguably one of the most well-known moduli problems in algebraic geometry. In this talk, I plan to take a stacky perspective and introduce the Picard stack as well as the Picard functor. Possible topics include the gerbe structure of the Picard stack, universal families and alternative definitions of the Picard functor. Familiarity with the sheaf theory on sites is helpful but I will try to review the theory as well.