Twitter is a piece of information network made up of 140-character messages called “tweets”. The brevity of the messages is key to its success: it takes very little time to scan a large amount of information. The tweets contain either a piece of concise information (a message, a question, a thought) or a weblink to more information elsewhere (a website, an image). Scanning recent tweets may be compared with scanning headlines in a newspaper, but with one major difference – you determine what kind of headlines you want to see ¹⁾.