Today, over one million people now make their living on eBay, which is astounding.

It's extremely hard to build a company with a product that everyone loves, is free and has no business model, and then to innovate a business model. I did that with Kazaa, had half a billion downloads but that wasn't a sustainable business.

Another differentiator is that Skype is free and simple to set up, and it costs us virtually nothing for a new user to join the Skype network, which is why we can offer the service for free.

When we look at investing, we always think about 'how defensible is this, how likely is it that somebody is going to copy this.' E-commerce tends to be something easy to copy because it's execution.

If you could utilize the resources of the end users' computers, you could do things much more efficiently.

If you can use a Web browser, you can use Skype.

You shouldn't be afraid of failure - when something fails, you think, 'What did I learn from that experience? I can do better next time.' Then kill that project and move on to the next. Don't get disappointed.