 Abstract 2-photon polymerization, TPP, is a powerful technique for creating bespoke polymeric devices and surfaces at the microscale. It has been applied to a wide range of applications such as optical, drug delivery, tissue engineering, and microfluidics. The field has evolved from standard acrylate or epoxy-based photopolymers to customize monomer formulations which can be used to alter the hydrophobicity, surface chemistry, mechanical properties, and more of the resulting structures. This review provides an overview of the fundamentals of TPP, including the mechanisms of radical and cationic polymerization and how they can be used to tailor the mechanical and functional properties of the resulting structures. Additionally, it discusses the various types of photopolymers available, including hard polyacrylates, soft hydrogel acrylic esters, epoxides, and organic slash inorganic hybrids. Finally, specific examples of each type of photopolymer are provided to illustrate their use in tissue engineering scaffolds, micrometrical, optical, and drug delivery devices. This article was authored by Sean O'Halloran, a Bay pundit, Andreas Heissa, and others.