Entrepreneurs are visionary people who have a knack for hatching new ideas and turning them into successful business ventures. Hip-hop mogul Russell Simmons created Def Jam Records and Phat Fashions; Bill Gross launched eToys and PETsMART.com; Oprah Winfrey founded Harpo Studios and Oxygen Media. For these enterprising individuals, launching startups is more than a job--it's a way of life.

What makes entrepreneurs unique is that they have a talent for identifying good ideas and transforming them into viable businesses and products. Turning a back-of-the-napkin idea into a real-live business isn't magic, however: entrepreneurs must be able to create a business plan, secure funding, target customers, and dedicate themselves wholly to a proposition that exists only in their imagination. The process requires an inexhaustible supply of drive and stick-to-itiveness.

And for many entrepreneurs, founding startups is like eating a Lays potato chip: you can't stop at just one. The thrill of launching the next big thing can be addictive, and there comes a point when entrepreneurs decide to turn their old creations loose and move on. For certain, selling an established startup to a larger outfit with more resources is often the best way to keep a business growing. However, cashing in serves a more important purpose for entrepreneurs--it frees them to chase after the next business adventure.