 So in my last video, I started talking about how I might want to move through the elements inside of my tree. And we refer to this as some type of traversal. No different than when we were operating in a list or in an array. I want to go through my elements. Now, since we're in a tree structure, this is a little more complex than say, for example, my linked list, which was just previous and next, and my array, which is just next. And so the first type we want to talk about is what I would call a pre-order traversal. The idea here is I want to visit myself. I'm going to use that term a few times. Visit myself before I move to any of my children and work off of them. Here's sort of the algorithm that we're going to be kind of playing with for a second. So if say, for example, pre-order, let's say I'm at some node and we call it in. So I'm right here. The first thing I want to do, like I said, is I want to visit in. You see I put air quotes around that. The idea behind visiting is that it could be anything. I could say print the elements of a print the children of a delete a rename a doesn't really matter what I'm doing. It's the matter of I'm sitting here and I'm actually going to do something with a before I start to move on. And as you can kind of see what I was just indicating with my my hand gesture. What I start to say is for each child of in pre-order in and well, sorry, pre-order child. And so what we're doing here is I visit say myself then every child I go to I visit them I do the exact same operation. So if we use the analogy of the file hierarchy, I deal with my current hierarchy and then I go to the very first folder and work off of it. Before I even get to these, I have to actually finish these. So in essence, if we were to say I just did pre-order a. So a, as we can see, visit that node first. So I'd be the first element that we traverse. Well, the next kind of step in there for each child of in B, C and D my children pre-order child. So we're starting at this one. This is actually going to be our next point. So imagine these are in, you know, some kind of order. This is where this kind of recursive call comes in. Notice when I come here, I visit B and then I immediately ask for each child of this node B pre-order its children. So I'm actually going to come down. I'm going to come down and do this child first. Then I move over. Then since there are no more, I can't go deeper. There's no more children for E. I go to F. Well, guess what? Since I'm at F, it has children, I have to go to those children before I can go further. Now that I'm done with sort of K in this essence, I go back to F. And since F was the last child of B, I go back to B. Now that I'm done with B, I can move over to C. And so C becomes my eighth element that's traversed. Then, as you can imagine, for each child. And then finally, since I'm done with H, that means I'm done with C, I can move to D. And that's sort of kind of, sorry, and there I've made my pre-order traversal.