If you are starting a new company, the first thing you need to do is to create a clear and concise (and preferably one-sentence) mission statement that explains exactly what your product or service does. That is one of the early keys to success and it enables your employees, the media, and your customers to effectively promote your brand. But Twitter seems to be an exception to this rule. From its earliest days through the buildup to its IPO, people have had a hard time describing exactly what it is. Quartz has put together a complete history of Twitter as told through tortured descriptions of it in the NYT. These days the service is ubiquitous enough that an accurate description has emerged: Twitter. It’s for Tweeting.