DI is a design principle, not a class for frameworks. DI just means to "inject" the dependancies of an object through constructor arguments, setters or by simpl

DI is a design principle, not a class for frameworks. DI just means to "inject" the dependancies of an object through constructor arguments, setters or by simply setting instance (aka member) variables. In other words, DI means that you don't use global variables (aka singletons). DI does not provide any more flexibility itself, but most DI frameworks encourage the usage of interfaces instead of concrete classes (which is a good thing) when it comes to defining dependancies. Sadly however, the fancy pants therm for using interfaces is "dependency inversion", because when using interfaces, the compile time and runtime dependancies of a class point in opposite directions. As you can imagine, this lead to a lot of confusion.