DI is a recommended design pattern and a software development technique used to implement the inversion of control (IoC) principle in software applications. IoC is the transfer of control of objects, object dependencies, and general application flow to a different component or part of the application.

While IoC and DI are sometimes used interchangeably, it's important to note that they are not identical concepts. Dependency injection is a specific technique for achieving IoC, but IoC encompasses broader techniques and patterns.

In DI, the dependencies of an object (i.e. the objects it relies on) are provided externally rather than created internally by the object itself. As an example, suppose Service X requires a function from Service Y to perform its operations effectively. Instead of Service X internally creating a new instance of Service Y, the recommended approach with DI is to have a separate component responsible for creating an instance of Service Y and then "inject" that instance into Service X.

The following sections highlight the methods you can use to achieve DI.