OSI Model and Encapsulation

The OSI Model (aka the Open Systems Interconnection model but you'll never see that) is a useful mental model of how internet communications system work and interact with each other.

Basically, the idea is that each level of the model is a different part of what is necessary for data to be transferred from one place to another. We will learn all about it as we go, so don't worry about memorizing anything... yet.

The competitor to OSI is the TCP/IP model, which is basically the same thing, but with less layers. It all shows the same thing, just with different levels of specificity.

Encapsulation

One useful thing we can use those models for is to visualize how encapsulation works. Encapsulation is the process of wrapping a piece of data in the routing information required to pass to the next level of the networking stack. Once it gets to the bottom of the stack at the physical layer and is actually sent across the network, once it is received "de-encapsulation" occurs, and each level of encapsulation is removed. Eventually, the data, as sent from the first computer finally reaches its destination.

What does that mean? How does it work? Don't worry for now, you'll be great at it soon enough.