JIncludes allows webmasters to easily:
• Create common HTML snippets to include in different articles (WYSIWYG editor friendly)
• Include PHP code and dynamically output contents in place
• Attach CSS files to single articles instead of putting the CSS code for all website's pages into only one stylesheet file (improving loading time and styling simplicity)
• Attach JavaScript files to single articles, with the same benefits.
Snippets are created on a sitewide basis and called with a {{keyName params}} from inside articles' text. You will choose the keyNames for the snippets you create. The use of parameters and the "block matching" option allow very powerful content elaboration.
To update the plugin after installation, you will find an update package. Please feel free to visit the project's wiki and to post to the project's forum if you need any kind of help :)