A subpoena issued in Pennsylvania demands the names of two tweeters who criticized the state's attorney general. Is this a breach of free speech?

Twitter's official app for the iPhone has finally appeared in the U.S. iTunes App Store. It is free and here is the link.

Many Twitter users were surprised Monday when their number of followers appeared to be zero. The temporary glitch was a side effect of a fix for another Twitter bug.

If you use Twitter, you may be wondering why you suddenly have zero followers and are following zero people. (If you haven't discoverd this yet, check out your Twitter homepage.)

Don't worry. Your followers aren't gone for good, and your social networking ego will be restored soon.

Twitter reset everyone to zero temporarily while it tries to fix a glitch in which users could force other users to follow them involuntarily. Users were abusing the loophole to make celebrities and others follow them after it became widely publicized on sites like Gizmodo. Twitter is currently trying to undo the mess and promises to restore your followers once all is resolved.

Your search results on Twitter will not include paid advertising tweets. Here is what you need to know.

Police in France believe they have arrested a man that hijacked Twitter accounts of several well-known people.