This chapter explores the pivotal roles of planar lipid bilayers and liposomes in advancing our understanding of protein function. These artificial membrane systems serve as essential models that mimic natural cellular environments, providing a versatile platform for studying protein-lipid interactions. We delve into methods for assembling planar lipid bilayers and liposomes, examining their composition and diversity, and the techniques employed to integrate membrane proteins for functional analysis. We consider the influence of osmotic dynamics on membrane behavior and protein interactions through pressure gradients and review studies of signal transduction in artificial membrane systems aimed at elucidating how proteins interact with lipids to mediate cellular communication. We also discuss the contributions of these systems to structural studies, involving techniques like cryo-electron microscopy and X-ray crystallography, to reveal high-resolution insights into membrane protein conformations. Discussing challenges and limitations, we review the biological relevance and technical constraints that shape experimental outcomes. Looking forward, we consider innovations in lipid bilayer model systems and new research directions that promise to expand their utility. This chapter underscores the continued importance of these systems as indispensable tools in unraveling the complexities of protein function within biological membranes.