Twitter Help.... @ and # Q's..?

[Hannah]

I'm quite new to twitter and really don't understand the following:
What does # represent/mean?
Is there an easier way of ensuring you @ the right person in reply? especially as a misspelling or error can send it to the total wrong person.. other than by memory?

Realllyyy appreciate it

[Vee]

The # sign represents a topic. For example: #HarryPotter. If you're using the twitter.com news feed and look to the right hand side of the feed, you'll see a bunch of #topics. They're called "trending topics" and basically if you click on them (or if you see a #topic on your feed, you can click on that as well) it'll take you to a page to show you what people are saying about the #topic.

As far as @replies go, you can always highlight and copy/paste the user's name or you can download seesmic desktop. It's integrated software for your computer. You can sync twitter and facebook updates onto it and you'll never have to get on either site again (unless you wanted to). It's really nifty, and it's what I use. When you type in the usertag for an @reply, it finishes it for you based on your list of people that you follow.

You can check it out here at http://seesmic.com/seesmic_desktop/air/