The rise and fall of Travis Kalanick, Uber's embattled billionaire founder who just resigned as CEO

Eight years ago, Travis Kalanick launched a startup called UberCab in San Francisco.

Today, Uber is a global behemoth and one of Silicon Valley's most successful companies - and one of the most contentious.

Uber operates in around 600 cities worldwide, and it's said to be worth nearly $70 billion.

The 40-year-old Kalanick is now said to have a net worth of more than $6 billion.

But Uber - and Kalanick - have been caught up in one scandal after another in recent months, leading to a four-month investigation, more than 20 firings, and finally, Kalanick's resignation from the company he created.

Here's how it all began.

Maya Kosoff contributed to an earlier version of this post.