On Wednesday, top social media executives will testify at a Senate Intelligence Committee hearing on what social media platforms are doing to prevent meddling in US elections. But what have they done already? And how is the search for online security affecting their bottom lines?

Jack Dorsey's payment company may be facing an uphill battle in the market.

Both young and charismatic CEOs were ousted from their own companies. One came back.

Now he has to figure out how to keep it interesting and bring people back.

The hard-to-define company still hasn't picked a permanent CEO.

Dorsey founded two multi-billion dollar businesses … and he isn't 40 yet.

When a tech company like Twitter goes public, the pressure is on to make money and lots of ideas get tried out.

A new book out details the sometimes-sordid history of how the social networking company got its start.