The rapid progress in micromanipulation technologies has created exciting new possibilities for the actuation, selection, and assembly of both biological and non-biological nano/micro-objects, with applications in microfabrication, cell analysis, tissue engineering, biochemical sensing, and nano/micro-machinery. A wide range of precise, flexible, and high-throughput manipulation techniques have been developed to meet these diverse needs. Among these, optoelectronic tweezers (OET) stand out as a cutting-edge technology that combines light stimuli with electric fields, utilizing the photoconductive effect of semiconductor materials. OET uses optical modulation of electric fields to directly control micro-object behavior in a flexible and non-invasive manner. This light-induced electrokinetic effect provides key advantages, including programmability, flexibility, versatility, high throughput, and easy integration with other characterization systems, distinguishing OET from many other manipulation techniques. In recent years, OET has gained significant attention, with rapid advancements across a range of scientific and engineering fields. This chapter aims to provide a comprehensive review of OET technology, exploring its underlying mechanisms, experimental setups, applications in both biological and non-biological contexts, commercialization efforts, and future prospects.