YouTube SEO is the practice of optimizing a YouTube channel and its videos to rank higher in search results on YouTube and Google, thereby increasing discoverability and views. It involves strategies like thorough keyword research for titles, descriptions, and tags, creating compelling video content and thumbnails, and encouraging viewer engagement like likes, comments, and shares. The goal is to align content with the YouTube algorithm, which considers metadata, watch time, and engagement signals to match viewers with relevant and engaging videos.