1. Debate. Blog is like a debate. The author explains their opinion and wants to see if it is acceptable to the readers. If not, then why? What's wrong with the presented point of view? Once readers express their opinion about the author's piece, a debate starts. The blog owner should also participate, encourage readers to talk about the issue. If someone criticizes the post, they should not be moderated. Negative opinion is also helpful for the debate.
2. Additional content. If the blog post is not very long, it contains lots of pictures or videos, the comments create additional content, which is valuable for Google (SEO).
3. Community. The real asset of the blog is a group of returning readers and people who write comments. They are usually the most active and might also recommend the blog to their friends. If such readers have their own blogs, the author can arrange some link exchange deals or find other ways of partnership to strengthen the community ties.
4. Trackbacks. People who post comments tend to mention it in their own blogs or social networks, so one's blog might get some additional exposure in various online resources. Exposure means more visitors and even more comments.
5. Personal relationships. It is always nice to get an answer or a comment from the owner of the blog because it means that they care about their readers. Being in a virtual relationship is the main feature which makes blog post, a news article or a press release different from the traditional media and more human-like.
6. Suggestions. Comments can be used as a perfect way to collect suggestions for the future blog topics. If the debate deviates from the main topic, it means that people would like to read a new post on the issues that have been discussed. The author can also ask for the readers' opinion on the topic. And not only the opinion. It can be additional resources for education, information on competitors etc.

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