Tutorial by Topics: inversion

The source code for large software applications is typically organized into multiple units. The definition of a unit normally varies by the programming language used. For example, code written in a procedural programming language (like C) is organized into functions or procedures. Similarly, code ...

The principle basically says, Class should depend on abstractions (e.g interface, abstract classes), not specific details (implementations). That means, You should let the caller create the dependencies instead of letting the class itself create the dependencies.