In-line Ajax Page (inap) displays the full contents of your posts and comments in-line without reloading the page or navigating away from your home page. The plugin displays an excerpt of your post (the same way Wordpress does when you use the_excerpt or a < !–more–> tag), but rather than making the user go to another page to read the remainder of the post, this plugin uses Ajax to download and display the rest of it when the user clicks a link to read more. After wards the post’s content can then be hidden and the user can continue reading your other posts. It uses a similar method to display comments and the add comment box and to submit comments.

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Inline Ajax Page V2.1, WordPress Plugin, WordPress