With an increase in the awareness of polymer viscoelasticity, several researchersin the textile industry have conducted rheological experiments to investigate the polymericmaterials they deal with. However, the experimental results can be interpretedmeaningfully when the polymeric materials are processed and analyzed based on viscoelastictheory. This review first describes the fundamental theories of linear viscoelasticity. Moreover, it provides various examples of linear viscoelastic studies on polydisperse polymermelts, polymer solutions, polymer blends, and reacting systems. The types of experimentsdepend on the measured viscoelastic functions. Viscoelastic functions aremathematically interconvertible within a linear viscoelastic range. However, numerical dataprocessing is necessary to practically apply theoretical relations to experimental results. Here, we review several useful numerical methods and algorithms. We hope this reviewcould be a helpful guide for researchers analyzing the viscoelasticity of textile materials.