System plugins operate every time a page on your site loads. They control such things as your URLS, whether users can check a "remember me" box on the login module, and whether caching is enabled.  New in 1.6 is the redirect plugin that with the redirect component assist you in managing changes in URLs.
Default on:
- Remember me Help
- SEF Help
- Debug Help
Default off:
- Cache Help
- Log Help
- Redirect Help
