Twitter

Millions of people use Twitter every day to share what they think and read, making the service a sort of global watercooler for everything from politics to sports. But Twitter is also a den of disinformation and harassment that the company's executives regularly condemn, though haven't fully addressed. As a business, Twitter's track record is mixed. The huge influence its service has on public discourse has, so far, failed to translate into a fast-growing business like many of its tech-focused peers.