What is Dependency injection (DI)?

Dependency injection is when one part of a system gives another part exactly what it needs to work, instead of that part having to find it on its own.

Imagine you're building a sandwich. Normally, the bread has to go out and get the peanut butter by itself, that’s hard work! But with dependency injection, someone else brings the peanut butter straight to the bread. The bread just needs to know where to put it, no running around needed!

Think of a robot who wants to clean your room. Instead of the robot having to find its own vacuum cleaner, you give it one when you turn it on. That’s dependency injection, you're giving it what it needs right at the start.

Without dependency injection, parts of a system have to search for what they need, like the bread searching for peanut butter. With it, everything gets what it needs quickly and clearly. This makes things easier to fix or change later, just like how you can swap out one type of peanut butter for another without changing the bread!