Reach in YouTube and social media marketing is the total number of unique viewers exposed to a video, Short, or channel over a defined period. It is different from impressions, which count every time the thumbnail loads, and different from views, which count actual video starts. Reach captures the size of the audience touched, regardless of frequency. Wider reach usually comes from better packaging, algorithmic distribution, cross-platform sharing, and subscriber-driven pickup, and it feeds directly into brand awareness and future audience growth.