One of the ways to promote our website, is to actively participate in forums and blogs on the theme of our page.
When we leave a comment in a blog, this is usually accompanied by a URL in the name of the person writing the comment, and that is where we get the link. It is clear that not all our comments will be published, but in those that are published we will achieve a double objective: a link to our page and possible visits from other users who see the comment interesting, and encourage them to visit the page of the author of the Blog Comment Service. What we should never do is SPAM , that is, put comments with the sole purpose of the link. Comments of the type "Good post", etc. They do not contribute anything.
In many cases, once the comment is written, it is retained for moderation by the webmaster of the blog, delaying the publication of the comment in some, even days or even weeks. When the comment is published automatically without waiting for an approval from the moderator, the blog is said to have "auto approval" comments.
Additionally, here you have 2 page relationships: some allow you to publish comments that are published immediately, that is, they are "auto approval", and another with comments "dofollow".