For both novice and experienced practitioners of solid-phase peptide synthesis (SPPS), the vast selection of commercially available linkers and resins has become something of a babel. The purpose of this unit is to clarify the situation, which is best understood by distillation to first principles, through an appreciation of chemical trends and consequences, as well as practical considerations. The most commonly used linkers and resins are presented and described in detail, along with a description of their development and common applications. Key protocols are provided so that the user may prepare appropriate linker-functionalized resins for the majority of peptide synthesis applications.