Outdoor advertising, or out-of-home advertising (OOH), is a longstanding mass communication method that reaches people in public spaces such as cities, transit systems, and commercial districts. This dynamic industry blends traditional static formats like billboards and street furniture with innovative digital networks featuring real-time content updates and programmatic buying. Leading companies manage diverse advertising venues including transit ads, mobile billboards, and digital screens, enhancing urban environments while generating revenue for public services. Regulatory frameworks globally govern advertising placement, safety, illumination, and environmental impact, reflecting local cultural values and urban planning priorities. Notable initiatives, such as São Paulo's "Clean City Law," exemplify efforts to balance commercial messaging with public space preservation, underscoring the essential role of outdoor advertising in modern urban life.