Adding captions to YouTube videos significantly improves search engine optimization (SEO) and increases the visibility of your content. Search engines like Google can crawl and index the text within captions, providing additional textual content for their algorithms to analyze. This makes it easier for search engines to understand the context and relevance of your video content, resulting in higher chances of your videos appearing in relevant search results. By incorporating relevant keywords and accurate captions, you enhance your video's discoverability, attract organic traffic to your channel, and ultimately grow your audience and engagement.