Speed is one of Twitter's defining traits. Unlike traditional search engines, which may take days or months to find and catalog new information, Twitter's search feature works in real time. When you hear about a story or a picture going viral on the Internet, Twitter is one of the primary engines of that proliferation.
Companies understand this. When someone praises (or trashes) its products or services on Twitter, that corporation instantly knows it. In the event of negative feedback, smart representatives quickly address the problem and make a positive impression in front of a very large audience.
Of course, the process works in reverse, too. If your company has angered a lot of people, just one raw, frustrated Tweet can snowball into a million more, as exasperated customers type their first-person accounts for all the world to see. Everyone can influence the conversation now, immediately and without censorship or moderation, for better or for worse.
It's not just companies that benefit or suffer at the little blue wings of Twitter. The same goes for politicians, celebrities, technology experts, fashion taste makers and just about anyone who wants to share ideas with the world. As their followers chime in with their own thoughts and feelings, Twitter threads become a ceaseless, searchable conversation on every imaginable topic.
Of course, the corny and the mundane will likely always make up the bulk of Tweets, but the same goes for most of human conversation. It's the conversations we share and get really excited (or sad) about that bubble to the surface of our collective consciousness -- and Twitter is there to document and spread all of it.
Whether Twitter continues to grow in popularity remains to be seen. But for now, no other communications service works the same kind of magic as Twitter. So Tweet away to your heart's content, because in a way, the whole world is listening.