What is Twitter?
Twitter is a microblogging platform which invites you to share what you're doing with the world - in 140 characters or less.
These short messages are called "tweets".
It also allows you to keep track of what other people are doing as well, either by monitoring their Twitter updates online, or - in some countries - by receiving updates directly to your phone in the form of SMS text messages.
How can I see who's really been tweeting about #bbcClickRadio?
If you'd like to share your thoughts on the BBC World Service Click radio programme with other listeners - and for them to be included in the stream of messages displayed here - you need to add a 'hash' to your message - #bbcClickRadio - to ensure it gets included in the feed.
If you don't have a Twitter account, you can sign up for one at Twitter.com. It's currently free.
You can also see who's recently been tweeting about Click, and the extent to which they follow each other on Twitter, by check out the hashtag community graph at http://bit.ly/bbcclickradiocommunity (case sensitive...!)
This application searches Twitter for the 100 most recent tweets sent using the hashtag, and uses this list of tweets to identify at most 50 people who have recently used the hashtag. For each of those fifty people, we then look up the (public) list of their Twitter friends (that is, other people they follow on Twitter). If a friend has also recently used the hashtag, we draw a line connecting those two people.
Remember, messages published in the Twitter stream are by individual Twitter users and The BBC and The Open University are not responsible for the content of them.