What is an external dependency?

So I have taken up playing chess. The great thing about Chess is that you have total control over the next move you make. And on the flip side: you have no control over the moves your opponent makes. None. In other words, you interact with another player, but you have no control over that player. In this particular case, you can say that the player is an external dependency.

To reduce this example to a general principle, an external dependency is:

• Code which your code interacts with, and which you have no control over. You’re basically stuck with it and you gotta work with it.

Have you been paying attention? What is an external dependency?

1. I have been using a library – and have been calling it in my code. Unfortunately, which I cannot open it up and change it. Is this library an external dependency?

2. I have borrowed a library book – and you cannot edit it in any way. You can only read it. Is this an external dependency?

3. I have to review my own first draft but I can make changes. Is this an external dependency?