How can I create an “excerpt” with text that won’t be displayed in the post itself?

I’m currently creating a new theme for my blog and I intend to make it in a magazine style manner.

So, to clarify the question in the title: what I want to do is to create a text assigned to the post, but not displayed in the post itself. Lets say that the user Tom writes a review of the movie Black Swan – what I want to be able to do is summarize that review in a sentence or two – and use that text as an “excerpt” on the front page.

Any ideas? It’s probably a lot harder than I think it is.

It’s not. I believe when you go to make a post, there’s a box just below it that says “Excerpt” Whatever you put in that box will only show up as the excerpt.

I tested it out and it works. You can view it on the website i’m currently developing here: http://www.kirschfamilycomputerservices.com/sam/wheresthefairness/

The first post. Note how the excerpt is different from the post itself!

Also, if you want to run it in a loop instead of making a post I think there’s a way to do that, too. check here: http://codex.wordpress.org/Excerpt

Good luck and hope this helped.