Posts: The articles, information etc. posted by the author/authors on a blog are called posts.
Comments: As the name indicates, they are the responses from people reading a blog post. It is customary for blogs to have such an interface for posts which allows users to post comments.
Categories: They are used to categorize blog posts under different heads for ease of access.
Permalink: All the blog posts are generally to be accessible by an independent URL, even if the post has been archived. Permalinks are the URLs to the blog pages.
Archives: Blog posts are stored by day and month. This system in blog terminology is called archiving.
RSS feeds: Many readers these days like reading a lot of blogs. It is not very easy for them to visit each blog each day and look for updates. RSS feeds help users to keep in touch with the new posts on these blogs. User simply needs to subscribe to the RSS feeds of a blog and whenever a new content is posted on a blog, the user will come to know by reading these feeds. RSS is a technology that provides a convenient way for users to distribute and receive information in a standardized format.
Atom: It is an emerging RSS format which attempts to unify all other formats in one standard format.
Blogroll: A list of all blogs which a blog subscribes to. These are generally displayed on the home page of the blogs.
Trackback: If a blog refers to another blog in one of its posts, the referring blog may send a notification or a trackback to the referred blog.
Ping: Ping is the term used to describe the process on sending out the signal of a trackback sent to other blog.