comes after television, personal computer and smartphone? And what will be the fourth screen in the modern world? Lately, the ICT industry seems to be calling 'digital signage' as the fourth screen. Digital signage is a digital imaging device that shows various information such as texts and images on a large, high definition screen in public places. Amid introduction of new technologies such as customized advertisement through face recognition and interactive touch, the digital signage market is growing further. In particular, Samsung Electronics and LG Electronics, with their unrivaled technologies, are leading the global digital signage market. The two companies hold the biggest and the third biggest market share, respectively. Let's meet the digital signage technologies, which are continuously evolving, and predict the future of digital imaging market.