Explore the fascinating world of bacterial transport in a lecture that delves into the physics governing microbial movement in both dilute and porous environments. Learn about the fundamental concepts and cutting-edge research in active matter, focusing on how bacteria navigate complex surroundings. Discover how environmental factors such as geometrical disorder, chemical fields, and hydrodynamic flows impact individual bacterial swim patterns and collective behaviors. Gain insights into the latest experimental methods, theoretical approaches, and engineering techniques used to study these microscopic organisms in controlled, complex settings. This talk, part of a comprehensive research school on active matter in complex environments, offers a valuable introduction for early-career scientists and highlights emerging directions in this exciting field of study.