The cut tags are very basic HTML codes that let you post just a teaser on the journal main page and then the rest of it gets tucked away on another page. Don't panic - the tags generate the page, not you. There are other tags for making things bold, italic, etc. If you'll follow the links below you'll get a pretty good idea of what I'm talking about.

http://www.livejournal.com/support/faqbrowse.bml?faqid=72

http://www.livejournal.com/support/faqbrowse.bml?faqid=75

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