Fortune's Fastest-Growing Companies

If you're looking for investment opportunities, check out the twenty companies profiled below. There are a few familiar names on the list -- like Apple, the world's most valuable company -- but many more you may never have heard of (like IPG Photonics, manufacturer of high-powered lasers, or 51job, China's largest worker-recruitment website). Click through the slides and let us know what you think in the comments below.

%Gallery-164560%