Spatial light modulators, as dynamic flat-panel optical devices, have witnessed rapid development over the past two decades, concomitant with the advancements in micro-and opto-electronic integration technology. In particular, liquid-crystal spatial light modulator (LC-SLM) technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude. These devices have gained significant interest in the nascent field of structured light in space and time, facilitated by their ease of use and real-time light manipulation, fueling both fundamental research and practical applications. Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications, covering topics as diverse as beam shaping and steering, holography, optical trapping and tweezers, measurement, wavefront coding, optical vortex, and quantum optics. Finally, we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.