This is certainly a reasonable explanation:
http://en.wikipedia.org/wiki/Inversion_of_control
I own this book: I'd recommend it for good coverage of many design principles, including IoC:
Agile Principles, Patterns and Practices in C#: Martin Fowler, Micah Fowler
You might also find these links helpful:
Two pithy "explanations":
IoC is sometimes known as the "Hollywood Principle": Don't call us, we'll call you
IoC = Marriage; IOC Container = Wife