So this is a seven layer model developed by the International Standards Organization in the early 19 eighties and O s stands for open systems Interconnection model.

And it's not a perfect model.

It's been around for a while, but it's It is ubiquitous in any sort of detailed conversation that you might have about networking, and it's still a pretty useful conceptual model.

I think you know, to reason about how different technologies fit together.

So you know, we'll refer to it from time to time just to kind of see how things fit in.

So, so far, we haven't talked too much about layers three through seven yet.

But we have been talking quite a bit about layer one in Layer two in the last few videos, and so later.

One is the is the physical layer.

So some of the things that we've talked about this layer include, um, the sort of physical means of encoding information.

So whether that's over copper or fiber or radio waves on, and we've specifically been talking about Manchester Code as one way of encoding data.

There are a couple others that we that we haven't really touched on an R Z and which is not returned zero and Kwame, which is the quarter amplitude modulation.

We may cover in some later videos on more advanced things, but just wanted to show you that there are some other things here, and then layer to is the data link layer, which has to do primarily with framing and frame formats.

And so we've talked about Ethernet framing, using the preamble and the inner frame gap to denote frames.

We've also talked about HDL see and using those those flag bites to denote frames on.

And then we've also talked about the frame format.

So the Ethan at logical Link Control, which is the Ethernet frame format that we that we just looked at or the PVP logical link control.

And so those air, basically all of the layer one, and later to technologies that will talk about for now.

But then, as we start to cover MME.

Or more of the layers in this model, I think we'll it'll help more to kind of see how things fit together.

We'll check back in here just to kind of see how things fit and how each layer sort of depends on the layers below it.