At the bottom of this page, there's a comment form that allows the user to submit a CommonMark (markdown) formatted comment about the article. All comments are moderated, so the comment will not immediately appear on the page after submission.
The comment is stored in a comments/ directory that resides in the directory for the associated piece of content (article). For example, this article resides on a file system, with the following path:
If a comment is submitted for this article, a directory will be created under <article directory>/comments/, and a markdown file with the comment's contents will be created there.
A file will also be created in this directory:
to help the moderation system list new comments needing review. The file is named using the comment ID, e.g.:
$:~/projects/gerbil/site/comment-review$ cat xms0bqd1.txt tutorials|uujjkdd9|xms0bqd1
How would you end up doing rate limiting if it became necessary?