Interactions between micro-swimmers and solid boundaries play an important role in many biological and technological processes. I will discuss recent results in experiments and simulations that aim to understand the motion of micro-swimmers such as bacteria, micro-algae, spermatozoa or active colloids in various confinements or structured environments. Our results highlight the complex interplay of the fluidic and contact interactions of the individuals with each-other and the boundaries to give rise to complex individual and collective behavior.