A module refers to a transportable unit composed of preassembled components from a process plant. The modularization approach aims to streamline facility layouts and shift a substantial portion of construction activities from the field to dedicated module yards, thereby minimizing on-site labor. In highly modularized setups, both small and large static equipment, as well as rotating machinery packagesDamping, are typically mounted on steel frameworks. A key element of modularization is the integration of equipment into these modules. Installing rotating or reciprocating machines on steel structures—rather than traditional concrete foundations—introduces distinct engineering challenges. Fabricated steel modules possess lower stiffness and damping characteristics compared to concrete, making it essential to assess how these structural properties affect the performance of mounted machinery. This requires specialized analytical techniques and tailored design strategies. This chapter explores the principles of modularization, various module types, structural configurations and loading conditions, and the methodologies used for structural analysis of modules.