The unique yarn textures obtained in twist texturing are due to varying amplitudes and wavelengths of unmatched phases in individual filaments, as well as the migratory patterns followed by the filaments. The migratory patterns are influenced by base yarn characteristics and their interactions with texturing conditions. Texturing conditions can be adjusted to provide the best interactivity with particular filament characteristics, promoting increased migration and fuller yarn texture. Researchers explain the role played by migratory patterns in the quality of flat and partially oriented textured yarns. The higher the migrational frequency, the higher the nodal frequency, crimp contraction, and crimp force in crimped yarns. Because migrational frequency is dependent on stress differentials between filaments of different orbits, migrational activity is lower in drawtexturing than in partially oriented yarn texturing due to reduced stress differentials. Microdenier filament yarns are poor feeder yarns for false twist texturing because a larger number of orbits with lower differentials are generated during the twisting of microdenier yarns.