Look for when the environment is changing - the big shift now is mobile Internet. It's really happening big-time. The way you interact with services on a smart phone compared to the Web is quite different, so there's a huge opportunity.

When we started Skype, if you look at analyst reports, no one forecasted it as a big business. Also when Google started, it was not fashionable to be in search. It's not trying to do the obvious - that's the hard part.

The telephone is a 100-year-old technology. It's time for a change. Charging for phone calls is something you did last century.

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

Surround yourself with smart, dedicated people - to build something isn't a one-man show. It's more important to have smart people who really believe in what you're doing than really experienced people who may not share your dream.

Skype is easy enough to use so that people don't need to be tech savvy - a lot of users just want to communicate with their friends and family, and they find this is the easiest, cheapest way. If you can use a Web browser, you can use Skype.