Numerous Eriophyoidea species (Acari) can induce galls on various host plant species. They are typically characterized by their small size and a reduced number of legs. The eriophyid female fundatrix initiates gall formation on species-specific host plants, typically targeting young plant organs. Additionally, the female can oviposit within the gall, where the nymphs feed, thus sustaining the stimuli for gall formation. Eriophyoids may cause simple galls such as erinea or hairy galls, and other most complex, such as blister, pouch, stem, flower, and bud galls. The life cycle, feeding behavior, dispersion, and gall induction by eriophyid are revisited herein, even though several species are not known or studied yet. These organisms are important due to their occurrence worldwide, their impact in economic plants, and their capability of transmitting viruses. Since they suck cellular contents with their diminutive stylets, eriophyids impact mainly the cells on which they feed and surrounding tissues. Nutritive cells may be observed in some galls, while in erinea, trichomes or emergences accumulate sugars in vacuolated cells. Some authors analyzed the physiological aspects of eriophyid galls and their impacts on plant yield, photosynthesis, and secondary metabolism. Associations with eriophyoids are also revised, demonstrating the potential of galls to shelter these organisms against predators. Integrative studies encompassing taxonomical, behavioral, anatomical, physiological, and biochemical approaches are essential for comprehending the impacts and remarkable diversity of eriophyoid galls. These studies are also crucial for proposing control methods, particularly when these pests affect significant crops.