What's the difference between @ and #?

[dedwarmo]

On twitter sometimes I see @someword and other times I see #someword. What's the difference?

[Chris]

@someword is creating a "Mention" of another user. #someword is a hashtag, which is a way of tagging things, like adding keywords. So:

@mygoodfriend I can't wait to get to San Francisco for #WWDC

Means that I'm mentioning the user "mygoodfriend," so mygoodfriend will see my message in his Mentions page on Twitter. It's also tagged "WWDC," so people can search on that text.

[barefootmeg]

@username indicates that you're either replying to someone (in which case the @username will be at the very beginning of the tweet) or that you're mentioning someone (in which case it could show up anywhere in the tweet). for example, someone might write, "i met up with @adamsandler at the party last night. he was wearing polka dot shorts." the handy thing about this is that even though you're not talking TO adam sandler, he'll see that he's been mentioned in your tweet. (the twitter app. that i use, nambu, has a "mentions" section where it specifically lists tweets like these.)

#tag indicates a company (often) or a trend (like the #upsetatrekkie trend when the movie came out) or anything main topic in a post. so if i'm talking about #google i'd put the hashtag on it so that people can easily note that i'm talking about the company. (you can do a search for "google" using the twitter search, but i've noticed that twitter apps. recognize the #word and make it linkable - when you click on it, it automatically does a search for that hashtag. just typing google without the # wouldn't provide the link in this case.)