Tags are indeed a vital part of OnPage Optimization. They play a crucial role in improving a website's visibility and search engine rankings. Tags such as title tags, meta tags, header tags, and image alt tags provide important information to search engines about the content and relevance of a webpage. They help search engines understand the context and purpose of the page, making it easier for them to index and rank it appropriately. Additionally, well-optimized tags can also enhance the user experience by providing clear and concise information about the webpage's content.