Explore the fascinating world of confined active matter in this comprehensive lecture by Sriram Ramaswamy from the International Centre for Theoretical Sciences. Delve into the behavior of objects that convert energy from their surroundings into directed motion when constrained within specific environments. Learn about various examples of active matter across different length scales, including biofilament-motor protein suspensions, swimming microorganisms, self-propelled colloids, and more. Discover how complex environments like soils, oceans, and the human body affect the individual and collective behavior of active matter. Gain insights into cutting-edge experimental methods, theoretical approaches, and engineering techniques used to study these systems. This lecture is part of a broader research school program on Active Matter in Complex Environments, providing early-career scientists with a pedagogical introduction to this exciting field.