Hashtags are metadata labels prefixed with the # symbol that categorize content by topic, making it easier for users and platform algorithms to surface relevant material. On YouTube, hashtags appear above the video title and within the description, and they can improve discoverability by associating content with specific topic searches. When used strategically, hashtags function as a lightweight form of YouTube SEO — connecting videos to trending topics, niche communities, and broader keywords clusters. For best results, hashtags should be relevant, specific, and used alongside a strong title and metadata strategy.