Domains and walls in ferromagnets are a paradigm for pattern formation in materials science. Domains are subregions of the sample Ω in which the magnetization m is nearly constant; the transition layers separating domains are called walls. We will focus on the technologically important ferromagnetic films. Mathematically speaking, the micromagnetic model is a non–convex, non–local variational problem for the magnetization m. It is characterized by several length scales: On one end, there are the scales given by the sample geometry (film thickness and film diameter) and on the other end, there are the scales which depend only on the material. This set–up drives the pattern formation on intermediate scales. In this lecture, we shall try to explain specific experimental observations on walls and domains in ferromagnetic films starting from the micromagnetic model. First, we shall try to understand domain formation neglecting wall energy. Then, we’ll take wall energy into account and will discover that there are different modes of walls. Finally, we’ll have to take wall interaction into account. We will use a mixture of heuristic and rigorous arguments and shall present some numerical simulations.