Cooperation in the natural world occurs across all scales, from molecular interactions such as the binding of receptors, to the large-scale migration of animals across continents. To uncover the principles and mechanisms driving cooperative behavior, researchers often focus on a few well-studied model organisms. In this talk, we will explore one of the most thoroughly investigated organisms in biology - the multi-flagellated bacterium Escherichia coli - from the perspective of applied mathematics. We will begin by introducing the key features of swimming at the microscopic scale, considering both the biological structure of the flagellum and the mechanical properties of Stokes flow. Next, we will examine two recent theoretical advancements in understanding the cooperative dynamics of bacterial flagella: an elastohydrodynamic mechanism that enables flagella to synchronize their rotation, and a load-sharing mechanism through which multiple motors distribute the torque required for movement. These models offer fresh insights into the biophysical role of bacterial multiflagellarity and highlight how the individual components of the flagellum contribute to the bacterium’s swimming behavior.