Comments are a way for visitors to add feedback to your posts and pages. If you choose to enable comments for your posts, then a comment form will appear at the bottom of the posts and people can respond to what you have written.
How to Leave or Read Comments
To leave a comment, you’ll need to be on the individual post page — you can’t leave comments on a blog’s home page, only a specific posts. To find the individual post page, click on the post title. This opens the individual post. Scroll to the bottom of the post; as long as the blogger has enabled comments, likes, and sharing, you’ll be able to leave a comment, like the post, or share it to social networks like Twitter or Facebook.
Blog owners are in complete control of the comments left on their blog. Users on the blog who have Editor or Administrator rights will have the ability to manage comments. You may also turn off comments if you don’t want to use them. You can show the latest comments on the blog home page by adding the recent comments widget to the sidebar if you wish.
Can I edit comments I left on someone else’s blog?
No. It is not possible to edit or delete any comments you have left on other WordPress.com blogs. Blog owners are in full control of the comments on their blogs, so you can try contacting the blog owner and ask them to edit or delete a comment for you. If the blog owner has not posted any contact information, you can try leaving a short comment asking how to contact them directly.
More Comment Features
There are some noteworthy comment features at WordPress.com such as:
Changing the Prompt
The instructions from this guide are referring to the WP Admin dashboard. You can get to this dashboard by adding /wp-admin to the end of your site’s url (e.g.: example.wordpress.com/wp-admin)
If you want to change the prompt that appears before the comment area (Common defaults are “Leave a Comment” and “What are you thinking?”), go to your dashboard, then Settings -> Discussion, and change the comment prompt to whatever text you would like.
The Perfect Host: Comment Moderation (The Daily Post, October 10, 2012)